A delighted Brennan hails the Gold Cup win as "the best day of my life"
Imperial Commander landed a famous Cheltenham Gold Cup win in a dramatic race after odds-on favourite Kauto Star fell four fences from the finish.
The 7-1 shot, ridden by Paddy Brennan, hit the front three from home with 2008 winner Denman and jockey Tony McCoy.
But Imperial Commander surged clear on the run-in to win by seven lengths and give Brennan and trainer Nigel Twiston-Davies their first Gold Cup victories.
Denman was second at 4-1 with Grand National winner Mon Mome third at 50-1.
Kauto Star was bidding for a third Gold Cup victory and a second in a row but the Paul Nicholls-trained 10-year-old looked in trouble early on with Ruby Walsh almost parting company with him at one fence.
Gold Cup was never a two-horse race - Twiston-Davies
The pair recovered to move back into contention, but a crashing fall ended their hopes, although both horse and rider got back to their feet unscathed.
The early pace was set by Carruthers and Denman but Imperial Commander, who was narrowly beaten by Kauto Star at Haydock in November, was never too far away.
McCoy battled hard on Denman but once the winner took a narrow lead from two out, he was never in trouble.
A delighted Brennan said afterwards: "It's by far the best day of my life. I'm speechless. It was a dream the whole way.
"I've just got to take time to thank my boss [Twiston-Davies]. He's the best boss ever - he's produced two horses this week [Imperial Commander and Champion Hurdle runner-up Khyber Kim] and I just had to steer them."
Twiston-Davies, who has won two Grand Nationals, added: "It's absolutely superb. I thought Kauto was in trouble some way out before he fell.
Gold Cup win 'hasn't sunk in' - Brennan
"All the press were saying our one didn't stay so we'll go for the Ryanair Chase next year!
"It's just absolutely brilliant. It's been very hard for us sat there with the third-favourite when all the talk was about Kauto and Denman but we always knew we were going to win."
Walsh acknowledged afterwards that Kauto Star had paid the price for his two errors during the race.
"You cannot afford to make mistakes like that in Grade One company," he said.
"Imperial Commander made a mistake in the King George and that was him done. I made a mistake and we were down. That's the way it goes in racing.
"His first one was a bad mistake. It knocked me out of position and I could not get him on an even keel.
"You can't make a mistake like that against horses of the calibre of Imperial Commander, Denman and Cooldine.
"You are always struggling and I was fighting a lost cause. It was a bad fall but he got up and there's not a bother on him. He cantered back down fresh as a daisy, not a bother on him."
Denman's part-owner Harry Findlay was delighted with his charge's display but also paid tribute to the winner's achievements.
"It was a great performance. I thought in running we were going to win it, but Imperial Commander has shown a lot of class and speed and all I can do is take my hat off to him," he said.
"Denman looks a National horse through and through and I'd be very surprised if he doesn't take in next year's race."
Imperial Commander's win proved to be the first leg of a 747-1 treble for Twiston-Davies.
Baby Run (9-2jf) landed the Christie's Foxhunter Chase, leading from start to finish under the trainer's son Sam before Brennan guided Pigeon Island (16-1) to success in the Johnny Henderson Grand Annual Chase.
Despite the Gold Cup win, Twiston-Davies admitted that the Foxhunter victory gave him most pleasure.
"I was hugely proud of Sam and he rode a beautiful race. The horse was a write-off when I got him, but we managed to get him back.
"That has to take the biscuit. It was a long run to the line, but he was lonely for company and came home with his ears pricked. He didn't look that tired.
"He'll go to the Aintree Foxhunters' next and he'll remain hunter chasing next season."
Despite his disappointment on Kauto Star and also on Master Minded earlier in the week, Ruby Walsh ended up as the leading jockey at the meeting for the fifth time.
His wins on Big Buck's in the Ladbrokes World Hurdle, Quevega in the David Nicholson and Sanctuaire in the Fred Winter meant he was level on winners with Barry Geraghty but a couple more second places saw him collect the trophy.
Three winners for Nicky Henderson - including the day's opening race with Soldatino (6-1) in the Triumph Hurdle - allowed him to win the Thomas Pink Leading Trainer award for the first time since 2000.
Two big outsiders were also returned at a meeting which was probably the best ever for bookmakers, Thousand Stars (20-1) - with Katie Walsh on board - and Berties Dream (33-1).
The Emma Lavelle-trained Pause And Clause (14-1) picked up the Martin Pipe Conditional Jockeys' Handicap Hurdle with Johnny Farrelly on board.
Cheltenham Gold Cup
1. Imperial Commander (P J Brennan) 7-1 2. Denman (A P McCoy) 4-1 3. Mon Mome (A Coleman) 50-1 11 ran
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