Western Warhorse caused a huge upset in the Racing Post Arkle Challenge Trophy at Cheltenham.
Champion Bumper and Supreme Novices' Hurdle winner Champagne Fever was an 11-4 joint-favourite to complete the Festival hat-trick and jumped superbly at the head of affairs under Ruby Walsh.
However, Western Warhorse tracked him into the straight under a confident Tom Scudamore and quickened up to lead after jumping the final fence. Champagne Fever did his best to battle back, but 33-1 shot Western Warhorse passed the post a head to the good. Champagne Fever's fellow joint-favourite Trifolium was four lengths away in third.
Pipe said: "He's been point-to-pointing in Ireland and jumped well at Doncaster, so even though he'd only had one run over fences, it wasn't a real worry. What happened at Kempton when he dumped Tom Scu and bolted might have been a blessing.
"Roger (Brookhouse, owner) wanted to run him in this, but I wanted to go for a nice handicap somewhere, so it's a good job Roger got his way.
"He's always shown lots of ability and the drop back in trip has suited. Tom has given him a really canny ride, because I told him to bounce out and make the running, but they were going a stride too quick, so he just dropped in. He has the hood on to help him calm him down."
Scudamore said: "I still can't quite believe that. I've won an Arkle, it's extraordinary. It was Roger Brookhouse who said drop him back to two miles. We were not expecting that. It's a great thrill and for a change I'm lost for words."
Mullins said of Champagne Fever: "He's run a fantastic race. You'd be disappointed with the result, but not the performance. That's it for two miles. We'll step him right up in trip next season."
Charles Byrnes, responsible for Trifolium, said: "He's run a very honest race. He could never quite get to Champagne Fever at the second-last, but I'm thrilled with his attitude as he could have thrown the towel in but he didn't. I imagine he'll stay at the same trip next season."
The major disappointment of the race was 2012 Champion Hurdle hero Rock On Ruby, runner-up behind Hurricane Fly in last year's Champion. He made a shuddering error at the third fence and Noel Fehily did remarkably well to keep the partnership intact. However, he was soon back-pedalling and never looked likely to land a telling blow.
Vautour struck for the powerful team of Willie Mullins and Ruby Walsh in the Sky Bet Supreme Novices' Hurdle, the opening race on day one of the Cheltenham Festival, in course-record time.
Walsh had the Rich Ricci-owned 7-2 joint-favourite quickly away to set the pace with Splash Of Ginge, The Liquidator and Valseur Lido close up. Gilgamboa ruined his chance with a bad mistake two out, while Irving, the other 7-2 joint-favourite, was struggling early on and could never get into a challenging position.
Up front, Vautour kept pulling out more as he stormed away to take his 100 per cent record to four since he joined Mullins from France. Nicky Henderson's Josses Hill came out of the pack to do best of the home contingent in second, a place ahead of his stablemate Vaniteux.
Walsh said of the six-length winner: "I rode him like a stayer, I wasn't going to drop him in, and he jumped brilliantly. I've been doubting him all week, but he's a serious horse. He was doing a hack all the way and he jumped super when I needed him."
Mullins said: "That takes the pressure off a bit. He was very keen over the first and second hurdles, but I think Ruby accepted he was going to be keen and let him gallop and use his stride.
"The next thing it was like he was on a different set of rails to the other horses. That's what I found amazing. I thought if he could keep that up he was going to produce a performance like he did, and he did. It was just the way he cruised in front. It's extraordinary that a horse can have that sort of control in a Supreme for one that everyone had down as stayer.
"He made a mistake and I was worried that might knock the stuffing out of him, but he picked himself up and jumped the last. You could see him the whole way (up the run-in) idling - he wasn't even racing. He has the size and physique, and on that performance I think we can't wait to get over fences with him.
"I thought he was good, but I didn't expect that. He has treated them like a bunch of maidens. He'll get two-mile-four and three miles in time, and Punchestown would be the obvious place to go."
Ricci said: "I'm completely made up by that. We always thought he was a good horse and since October I thought he was our best novice. The credit has to go to Willie and Ruby - they are the stars."
Henderson said of his placed horses: "They have both run fantastic races, but in a way it's annoying for them to run so well and get thumped like that. My Tent Or Yours, Darlan, Binocular and Sprinter Sacre have all been placed (in the Supreme) and come on for the race."
Alan Spence, owner of Josses Hill, said: "His scope was all wrong and Nicky said he could have done with another week, but he wouldn't have beaten the winner in another week. He'll go chasing next year."
Sgt Reckless finished strongly to grab fourth place for Mick Channon, who said: "He was in a good position at the start but he got squeezed and lost his place. He stayed on from a mile back. We've been waiting for some decent ground and I don't see why he shouldn't run again somewhere."
Irving was sent off the other 7-2 joint-favourite but he could finish only ninth. His trainer Paul Nicholls said: "He was too far behind coming by here (the stands) the first time for my liking. Ruby gave his horse a peach and he looks a very smart horse. I'm disappointed, but he'll be back and there'll be another day."
Holywell followed up last year's win in the Pertemps Hurdle Final with a game victory in the Baylis & Harding Affordable Luxury Handicap Chase at Cheltenham.
Ma Filleule took a narrow lead over the final fence, but Holywell (10-1) battled stoutly up the hill to get his head in front and keep the mare at bay by a length and three-quarters. The Package was seven lengths away in third, with Green Flag fourth.
Richie McLernon was the lucky rider for the second year running as Tony McCoy was aboard Jonjo O'Neill's other runner, the 7-1 favourite Alfie Sherrin, who was successful in this race for owner JP McManus in 2012.
McLernon said: "This lad has got a home for life with me if he needs it! He was dynamite. He jumped brilliantly and travelled - I took him some places and he got me out of them every time. He has a great trainer, the best in England and Ireland - he's brilliant and absolutely gifted. Today is what it's all about."
O'Neill said: "He's a great little horse to come back here and do that. Early on in the season he slipped into a fence at Carlisle and lost his confidence a little bit. It took him a while to get going and then we thought we had him going at Catterick.
"Then he was fairly average at Doncaster, I know he won but he was disappointing and I thought 'the fences are going to look very big on him at Cheltenham'.
"He's gutsy and Richie had him in the right place. He gave him a great spin and I only saw him miss one (fence). I'd say a big field and a good gallop suits him down to the ground. It's magic (to get a Cheltenham winner)."
Gary Moore is confident a return to Cheltenham will not be a problem for Sire De Grugy as he looks to justify favouritism in the BetVictor Queen Mother Champion Chase on Wednesday.
With Nicky Henderson's reigning champion Sprinter Sacre the biggest absentee from this year's entire Festival after suffering a heart condition earlier this season, the two-mile chasing division has gone from being a one-horse show to a wide-open affair.
Sire De Grugy has undoubtedly taken up the mantle as the one to beat following victories in the Tingle Creek at Sandown, the Desert Orchid Chase at Kempton and the Clarence House Chase at Ascot, with each effort more impressive than the last in the hands of the trainer's son, Jamie.
The eight-year-old's one defeat this season was at Prestbury Park, however, when beaten by Nicky Henderson's fellow Champion Chase contender Kid Cassidy, and he was also behind the champion trainer's other leading hope, Captain Conan, in novice company at the track in November 2012.
Moore said: "The horse is fine. I wouldn't say he's better than he's been all season, but I think he's as good as he was going into the race at Ascot. Hopefully that will be good enough. Obviously I would prefer it if there was more give in the ground, but we can't help what the ground is and we'll get on with it.
"I think people are trying to find ways to get him beat and everyone is entitled to their opinion, but I'm not worried about the track. His jumping has been so much better this year. He's matured and having Jamie ride him makes it better all round.
"Whatever happens, he's had a great season already. He's won two Grade Ones and a Grade Two so he's done his bit. He probably didn't get the credit he deserved earlier on this season but he has done now. Sprinter Sacre was a beast last year but that's racing. One day you're up there, the next day you're down."
Last Instalment and First Lieutenant will both be declared for Friday's Betfred Cheltenham Gold Cup, according to Gigginstown House Stud's racing manager Eddie O'Leary.
First Lieutenant was among the leading contenders for the Ryanair Chase on Thursday, having chased home Cue Card in the race 12 months ago, but is not among the declarations.
Doubts remain over the participation of Hennessy Gold Cup hero Last Instalment in the Gold Cup due to the drying conditions at Prestbury Park, but O'Leary insists it is not out of the question both horses will line up, if the ground is suitable.
O'Leary said: "We have decided to run Rathlin in the Ryanair and both First Lieutenant and Last Instalment will be declared for the Gold Cup.
"No decision has been made (on whether Last Instalment) will run.
"We could run both horses if the ground is suitable, but at the moment, it looks as though the ground would favour First Lieutenant.
"We'll just have to see what happens."
Big Buck's and Annie Power feature among a field of 12 declared for Thursday's Ladbrokes World Hurdle at Cheltenham as the former bids to regain his stayers' crown.
The Paul Nicholls-trained 11-year-old chalked up four successive World Hurdles from 2009 to 2012 as he swept to 18 consecutive victories over the smaller obstacles.
However, he was forced to miss last year's race through injury and only returned to action in January, when he was third behind Knockara Beau in the Cleeve Hurdle on this course.
He showed the fire was still there and is expected to come on for the run in the hands of Sam Twiston-Davies, who rode him for the first time in that contest.
Ruby Walsh, who guided Big Buck's to many of his victories, partners Willie Mullins' undefeated mare Annie Power.
Mullins has also left in Quevega, who runs in the OLBG Mares' Hurdle on the opening day, and the trainer said: "It's just a precaution in case anything untoward happens."
Gordon Elliott's Mala Beach and Rule The World, from the Mouse Morris stable, are the other Irish horses declared at the 48-hour stage.
As well as Big Buck's, Nicholls has Celestial Halo, Salubrious and Zarkandar.
Cleeve runner-up At Fishers Cross, last year's Albert Bartlett Novices' Hurdle victor, and More Of That both carry the JP McManus colours.
Completing the line-up are last year's Coral Cup scorer Medinas and Reve De Sivola, who was fourth in this race 12 months ago.
Al Ferof, Benefficient and Dynaste are among 12 runners in Thursday's Ryanair Chase at Cheltenham, with First Lieutenant a significant absentee.
First Lieutenant was runner-up behind Cue Card in the two-mile-five-furlong Grade One 12 months ago, but the Mouse Morris-trained nine-year-old appears bound for a tilt at the Cheltenham Gold Cup at this year's Festival.
Benefficient and Dynaste were first and second respectively in the 2013 Jewson Novices' Chase, which is now sponsored by JLT, and will lock horns again.
Tony Martin's Benefficient arrives on the back of a Grade One victory at Leopardstown's Christmas Festival, but the David Pipe-trained Dynaste must overcome a disappointing display in the King George VI Chase at Kempton.
Al Ferof has good form at Prestbury Park as a former winner of the Paddy Power Gold Cup, but was a well-beaten third in the King George and finished a long way behind Harry Topper in the Denman Chase at Newbury last month.
Ireland is well represented with Benefficient joined by Boston Bob, Hidden Cyclone and the Morris-trained Rathlin.
The latter is Gigginstown House Stud's representative, in First Lieutenant's absence, and racing manager Eddie O'Leary gives the nine-year-old an outside chance.
He said: "Rathlin is well and beat Hidden Cyclone on better ground in Galway last summer. Hidden Cyclone is one of the leading hopes for the Ryanair, and our fellow is one of the rags, so we'll see what happens. We think he's got a sporting chance."
Hunt Ball, Kauto Stone, Medermit, Menorah and Rajdhani Express are others to feature, with Cantlow having been declared to run on Tuesday.
Willie Mullins has confirmed ante-post favourite Felix Yonger will be joined by stable companions Djakadam and Mozoltov in Thursday's JLT Novices' Chase at Cheltenham.
Felix Yonger has victories at Punchestown and Navan to his credit this season and filled the runner-up spot on his last two appearances at Limerick and Leopardstown.
Djakadam has looked the part in winning his two starts over fences, while Mozoltov was a bloodless winner on his latest start at Naas.
Mullins said: "Djakadam has travelled over and is an intended runner on Thursday.
"With Felix Yonger and Mozoltov as well, hopefully we'll have the three runners."
Asked which horse stable jockey Ruby Walsh will ride, Mullins said: "I'm not sure. That hasn't been decided yet."
Jason Maguire will miss the Cheltenham Festival after he suffered a fractured sternum and bleeding on his liver in a fall at Stratford on Monday.
The Grand National-winning jockey was partnering the John Quinn-trained Scots Gaelic in a two-mile handicap hurdle when he was unseated at the second flight and was kicked in the stomach by another horse.
Maguire was airlifted to University Hospital Coventry, where X-rays revealed significant damage.
Niall Hannity, a friend of Maguire, said from the hospital on Monday evening: "He has fractured his sternum and he's got bleeding on his liver.
"He's definitely out of Cheltenham and his wife, Lauren, is with him."
Maguire was due to have three rides on the first day of the Festival on Tuesday, including Un Ace in the Sky Bet Supreme Novices' Hurdle.
Conditional jockey Ciaran McKee, who rode outsider Descaro for trainer John O'Shea in the same race in which Maguire was injured, fell at the third hurdle.
McKee was briefly knocked unconscious and was taken to the same hospital by road ambulance.
Stratford clerk of the course Stephen Lambert said: "Ciaran was unconscious for about three minutes."
Willie Mullins is confident Quevega has arrived at Cheltenham as good as ever ahead of her bid for an historic sixth consecutive victory in the OLBG Mares' Hurdle on Tuesday.
The incredible 10-year-old joined five-times Gold Cup hero Golden Miller as the Festival's joint-winning-most horse when overcoming adversity to raise the roof at Prestbury Park last year, having almost come down when hampered by another horse running down the hill.
As she has done for the last four years, Quevega is making her first appearance of the season and her trainer, who also saddles Glens Melody in the race, admits getting his wonder-mare to her peak without the aid of a prep run is a task he relishes.
Mullins said: "Quevega looks good, as does Glens Melody, and they both appear to have travelled over well. She (Quevega) was well ahead of schedule this year, so much so I was contemplating giving her a run at Punchestown.
"My owners don't want to breed from her, they want to race. As a trainer I find it as personally satisfying as anything to produce a horse to go back there year after year. When they have ability, you mind that ability and pick the races."
Glens Melody has won successive Listed prizes in testing conditions at Warwick, but Mullins feels ground conditions could be detrimental to her chance.
He said: "Glens Melody has been to England three times this season and has won twice. She's in good form, but the drying ground would be against her."
Ruby Walsh, who has ridden Quevega to each of her Festival triumphs, said: "She's in really good form and even just to get to Cheltenham six years in a row is unbelievable. I'd say she's in good nick."
Highland Retreat gave Harry Fry his first winner and the young trainer admits he would thrilled if she can pick up minor honours behind Quevega.
He said: "She has done nothing but improve. We're all trying to beat one mare, she can't keep on winning, but if we finished second to a legend like her, we'd be over the moon. She has come a long way since being my first winner, and has improved 20lb this year alone. It's a drop in trip but there'll be a strong pace."
Second in the ratings behind Quevega is John Quinn's Cockney Sparrow, runner-up in the Fighting Fifth at Newcastle earlier in the season but last seen falling behind Annie Power at Doncaster. Doyly Carte filled the runner-up spot that day and though she was well beaten at Kelso a month ago, trainer Donald McCain is confident she can bounce back.
He told Betfair: "She ran in the Morebattle (Kelso), but probably shouldn't have done as she didn't like the ground. She ran OK, but should have run a lot better. On nice ground she should get the two and a half miles and she'd have an each-way chance."
Down Ace is unbeaten in five starts for Fergal O'Brien and won a bumper at Cheltenham last April. The Gloucestershire trainer said: "She has won all five starts for me, including a Listed race at Taunton, so she deserves her chance. I know she's running against Quevega but if she shows her best form, she can finish in the first three or four at a big price.
"I'll be disappointed if she's not in the frame as she's tough and genuine."
Sixteen 16 mares have been declared, with French challenger and last year's runner-up Sirene D'Ainay again in the field. Uddy is another contender from across the Channel, while other Irish runners include Jessica Harrington's Cailin Annamh and Jarlath Fahey's Jennies Jewel.