Synchronised landed a dramatic race for the Betfred Cheltenham Gold Cup in the hands of champion jockey Tony McCoy.
The 8-1 shot, owned by JP McManus and trained by Jonjo O'Neill, only took the lead after jumping the last.
He galloped on strongly to head The Giant Bolster (50-1) and strike by two and a quarter lengths, with last year's winner Long Run, the 7-4 favourite, only third - another three-quarters of a length away.
Dual winner Kauto Star was pulled up at the ninth fence by Ruby Walsh after losing his place.
McCoy said: "It's great for Jonjo and JP McManus.
"He's really delivered today.
"He was off the bridle the whole way and when I missed the third-last I thought my chance had gone."
McCoy, who was securing his second Gold Cup victory after Mr Mulligan struck in 1997, added: "He's an amazing horse and it was an amazing performance.
"I'm so pleased to win it for JP as he's been so good to me.
"Jonjo has done an incredible job. I've got a Grand National and a Gold Cup out of the man and I love him to bits.
"Jackdaws Castle looks a closed shop with JP and just a few other owners and I can't understand why he doesn't get more horses."
Trainer Paul Nicholls said Kauto Star, whose participation in the Gold Cup was in jeopardy following a schooling fall a fortnight ago, had returned from the race unscathed.
He said: "He's absolutely fine.
"Ruby wasn't happy after he'd jumped a couple of fences and we said if he wasn't happy to pull him up, and he's done the right thing.
"There's obviously something tweaking him."
Midnight Chase set out to make all of the running and initiated a strong pace, with Kauto Star and Long Run close up.
There was drama at the second fence when What A Friend, part-owned by Sir Alex Ferguson, fell.
Soon after it became evident Walsh was not happy with Kauto Star and pulled him up.
Time For Rupert got the better of Midnight Chase before four out, but he was soon swamped.
The Giant Bolster then looked like landing a major shock as he took the lead on the turn for home.
Long Run was in the front rank, but Sam Waley-Cohen was hard at work on him and he failed to show the same acceleration that won the race 12 months ago.
Burton Port also tried to close, but it was Synchronised who was delivered to perfection by McCoy as his stamina proved crucial.
O'Neill, who was securing his first Gold Cup as a trainer, said: "AP was brilliant on him, he knows him so well.
"Our big worry was keeping him in the race as, if he makes mistakes, he gets behind.
"A lot of work has gone into him at home so was a great team effort from the yard.
"He only came right in last 10 days or so and we weren't really confident.
"He flowered in the last few days and it was spot-on timing.
"It's fantastic to win it as a trainer. It's a big team effort.
"I knew the one thing he would do was stay - the big problem was keeping him in the race.
"AP got him into a great rhythm."
David Bridgwater said of runner-up The Giant Bolster: "He was brilliant, but I've always said this is an exceptionally good horse and he should have been about 16-1, not 50s.
"He jumped super, and it was a wonderful race.
"Hopefully we'll be back here next year and hopefully there'll be some big race to win before then."
Nicky Henderson said of the defeated champion, Long Run, and fourth-placed Burton Port: "I'm thrilled with my two boys and I have to give credit to the winners.
"JP is one of the stalwarts of National Hunt racing and Jonjo and AP are superstars.
"You have to say Long Run was not quite good enough on the day - he was always struggling to get to the pacemakers, but Sam (Waley-Cohen) rode a great race.
"I'd imagine they'll both got to Aintree, the three-mile race (Betfred Bowl) would be good for Long Run.
"I don't know about Burton Port, I'll have to talk to Trevor (Hemmings, owner) but you'd say there's no reason why he wouldn't go to the National as it's the only chance he'll get to run off 11st 7lb."
Sam Waley-Cohen added: "I'm very disappointed he didn't win, but I'm not disappointed in the horse - he's run all right.
"When landing over the last I thought his stamina might see it out, but it didn't."
McManus had never before won a Gold Cup, and was understandably jubilant.
He said: "It's a very special day, a very special moment - for Jonjo, for AP and for their families.
"It gives everybody a great lift and I just feel very, very proud."
Kauto Star's owner, Clive Smith, said it was "90% certain" the legendary 12-year-old would be retired.
He said: "The horse seems well in himself, but I've had a word with Ruby (Walsh).
"He said he jumped the first really well and the second really well, but when he went to the water jump he just stretched a bit and possibly felt a pain inside.
"Ruby didn't want to go on because of that - It was probably from the tumble he had two weeks ago.
"I think we probably will retire him. We said we wouldn't say anything today, but I think it's a very good bet we'll do that.
"What a great career he's had and he's been a wonderful horse. I've been so proud to own him and also the support of everybody has been absolutely tremendous.
"I would say it's 90% certain that he'll be retired.
"Someone will have to come up with a very good reason for me not to retire him."
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