Dodging Bullets, bred by Flat jockey Frankie Dettori, won the Queen Mother Champion Chase at Cheltenham for rider Sam Twiston-Davies and trainer Paul Nicholls.
The 9-2 chance won by one and a quarter lengths from Somersby (33-1) with Special Tiara (18-1) third.
Last year's winner Sire De Grugy finished fourth while the 2013 victor Sprinter Sacre - in his second run in 15 months after a heart scare - was pulled up.
Victory gave Twiston-Davies and eight-time champion trainer Nicholls a double after Aux Ptit Soins won the previous race, the Coral Cup.
Nicholls said: "I know the other two were past champions but I couldn't see why they were behind us in the betting, it must have been on sentiment."
Dettori praised the winning jockey for a "fantastic" ride and said the horse was "gutsy".
|BBC horse racing correspondent Cornelius Lysaght|
|"At their first Cheltenham Festival since teaming up, the wins of Aux Ptits Soins and, more particularly, Dodging Bullets were hugely significant to the Nicholls/Twiston-Davies association - it cemented it.|
|"However successful during the rest of the year, it's at the major events, like Cheltenham, where reputation-sealing wins are to be found.|
|"Ground conditions had, as trainer Gary Moore feared, probably dried up too much for Sire De Grugy, but he'll be back, though whether the same applies to Sprinter Sacre is surely a moot point."|
"He was bred to win the Derby, but this is second best. It's the equivalent of the 100m final at the Olympics and what a horse," said the Italian.
And Nicholls completed a treble when 25-1 chance Qualando, ridden by Nick Scholfield, won the day's sixth race - the Fred Winter Handicap Hurdle.
The Champion Chase, in which Champagne Fever was a morning withdrawal, was billed as a battle of the champions.
But Sire De Grugy, who has had an interrupted season, and Sprinter Sacre struggled to keep pace as the two-mile contest developed.
Three-time champion Flat jockey Dettori, famous for his Magnificent Seven winning spree at Ascot in 1996, has played down his role in breeding the seven-year-old, but revelled in this triumph at the home of jump racing.
It was a fifth Champion Chase victory for Nicholls, who also scored with Call Equiname (1999), Azertyuiop (2004) and Master Minded (2007 and 2008).
Other Day Two Highlights
Trainer Willie Mullins, who scored a historic four-timer on the opening day, clocked up a fifth win of the meeting with Don Poli in the RSA Chase.
Jockey Bryan Cooper triumphed on the 13-8 favourite, a potential Gold Cup candidate next year, 12 months after breaking his leg at the same fixture.
One bookmaker paid out on Mullins being the top trainer with just a third - 9 of 27 - of the races having been run.
The opening Neptune Hurdle went to 9-1 chance Windsor Park, ridden by Davy Russell for Dermot Weld.
Retiring champion jockey AP McCoy, without a win so far, was second on Parlour Games.
Russell was scoring in the same purple and yellow colours of owner Dr Ronan Lambe, for whom he won last year's Cheltenham Gold Cup on Lord Windermere.
Photographer Patrick McCann suffered a broken leg when a horse was carried out, went through the rail and caught him during the Cross Country Chase.
McCann, who works for the Racing Post, could have been more badly hurt but took evasive action as the unexpected drama unfolded.
Nina Carberry, on Quantitativeeasing, was forced to the left by another horse in an incident which went viral on social media.
Russell completed a Wednesday double as he emerged the winner on 16-1 chance Rivage D'or, trained by Tony Martin.
Quotes of the Day
"As long as he stays in Ireland, I'm dead happy," - Paul Nicholls, after a treble himself, on the success of fellow trainer Willie Mullins, who has five victories.
"I haven't shouted like that since watching my beloved Arsenal." - Frankie Dettori, breeder of the Nicholls-trained Queen Mother Champion Chase winner Dodging Bullets.
"It is a massive win and hopefully means I can keep hold of my job for years to come." - Winning rider Sam Twiston-Davies jokes about his role with Nicholls. He was appointed first jockey less than 11 months ago.
Jockey Tom Scudamore overcame a tardy start by Moon Racer, trained by David Pipe, to lead a 1-2-3-4 for horses trained in Great Britain in the concluding Champion Bumper.
Afterwards, former trainer Michael Dickinson - who made history by saddling the first five home led by Bregawn in the 1983 Cheltenham Gold Cup - was among those to congratulate him.
"I emailed Tom after he took the wrong course at Cartmel earlier in the season and was banned," Dickinson told BBC Sport.
"I said Tommy Stack did the same thing years ago, and there was no reason why Tom wouldn't go on to be champion jockey."
Victory made it six wins for Great Britain against the eight of Ireland, with 13 races to come.
Trainer Paul Nicholls bids to build on his Wednesday treble when he saddles two leading contenders in Thursday's World Hurdle.
Saphir Du Rheu and Zarkandar will try to fill the void left by Big Buck's when they run in the three-mile contest (15:20 GMT).
Nicholls won the race four times with his great stayer, who is now retired, but hopes his new generation can shine.
Meanwhile, the Gordon Elliott-trained Don Cossack is favourite for the Ryanair Chase at 14:40.
Saphir Du Rheu carries the same red, black and white silks of owner Andy Stewart's family as Big Buck's and will be ridden by stable jockey Sam Twiston-Davies.
"Sam thinks he may win a Gold Cup with him one day. Whereas Big Buck's didn't jump a fence, this lad will jump in the future some time as he is a big, scopey horse," said the trainer.
Rider Noel Fehily believes Zarkandar has a better chance than when he finished fourth in the race won by More Of That last year.
"He's in much better form this year and hopefully he has a great chance."
You can watch an expert preview of day three with former Gold Cup winning jockey Andrew Thornton and commentator John Hunt on theBBC Radio 5 live website.