Paul Nicholls has confirmed the incredible Kauto Star has run his final race.
The winner of two Cheltenham Gold Cups and five King George VI Chases, Kauto Star was pulled up on his final start in last season's Gold Cup.
Connections have taken their time to make a final decision over whether the 12-year-old should race on, but the champion trainer and owner Clive Smith have decided to call time on a brilliant career.
Speaking in his Betfair column, Nicholls said: "The end of an era has finally arrived. Clive was here this morning and we have taken the decision to retire Kauto Star."
Nicholls revealed in September connections would consider giving the legendary chaser one last run in the King George at Kempton on Boxing Day, but after seeing him on the gallops in recent weeks, he feels now is the right time to draw stumps.
"We have had nine superb years with the horse but, after seeing him in his work these past few weeks, myself, Clifford (Baker, head lad) and Dan (Skelton, assistant trainer) were of the opinion that the time had arrived to retire him," Nicholls said.
"Of course, as owner, the final decision rested with Clive, but he agreed that the horse had done enough.
"Don't get me wrong, Kauto looks and feels as vibrant as ever, as those who saw him at our owners' Open Day last month would testify to. He was mad fresh that day and continues to be as alert as ever and very, very well in himself.
"But I suspect Kauto will be like that when he is 20 years old.
"And, deep down, we know he has done enough - and in some ways I think we have to protect him from himself. And maybe ourselves, too. If he did go to Kempton and win or run well, would you really want to run him - or be able to resist the temptation - in the Gold Cup?
"I am not so sure."
Similar questions about whether Kauto Star should be retired were asked last summer, after he was pulled up in the 2011 Punchestown Gold Cup.
But he proved all the doubters wrong with a scintillating comeback win in the Betfair Chase at Haydock before claiming the King George yet again.
"Kauto is signing off in full health and after a season in which he proved so many people wrong by winning a fifth King George and a fourth Betfair Chase, to add to his two Cheltenham Gold Cups and Tingle Creeks," said Nicholls.
"Who wouldn't want to train a horse of this quality any more? He is a once-in-a-lifetime horse, after all.
"Ever since he won on his debut for me at Newbury on December 29, 2004, the horse has consistently proved himself a class apart. And a £1m Betfair Million bonus in 2007 and 16 Grade One wins later, who would bet against him going to Kempton in December and making it number 17?
"But sometimes, you have to listen to your head and your heart, and both told me that retirement was the only option.
"You are a long time retired - as a certain Sir Alex Ferguson soon realised after stating his intention to step down as United manager some 10 years ago - and particularly if you are as naturally exuberant, intelligent and inquisitive as this great horse.
"I get that.
"Who else is going to put the up-and-coming youngsters in their place on the five-furlong gallop now, and put a smile on Clifford's face every morning - no mean feat that! - if he is retired?
"But, knowing Kauto, he would still be coming back in after grass at the age of 14 still looking and working brilliantly, and giving us that burning question to answer.
"And delaying my honest take on the retirement question would have probably been just selfishness and stubbornness on my part too - the equivalent of a football manager desperately clinging on to his best, if ageing player - and sometimes you have to look to the future and at the bigger picture.
"But at the end of the day Kauto is Clive's horse, not mine. And he made the call this morning. And a brave and difficult one it would have been, too, so all credit to him.
"But Kauto is also a public horse now, every bit as much as Desert Orchid, and to us here at Ditcheat that had to be a factor in the decision to retire. And while it would have been brilliant to go out on a winning high - remember Dessie's last race was a fall at Kempton - I don't think anyone present at Cheltenham last March would view Kauto's final appearance on a racetrack as a failure.
"The spontaneous applause he got from the crowd when he was pulled up genuinely lifted the spirits of all the team here - and it is the team here, from Clifford down, and Clive, that made Kauto what he became - at what was a low moment.
"Disappointment was immediately replaced by pride, and that is the overwhelming emotion I feel when looking at the horse.
"Ever since then, Clive and I have discussed retirement at regular intervals.
"But now the decision has been made it will be very strange to look out of my office window and not see Kauto's head and Denman's arse sticking out the main two boxes - or indeed Clive's Master Minded, for that matter.
"Because Kauto Star will be the hardest of acts to follow.
"He has given me my best days in the sport and, even though the Gold Cups and King Georges are the pinnacles for any staying chaser, with his 2009 Kempton win breathtakingly impressive, the raw emotion that followed his Haydock win last November will live longest in my memory.
"I had to hold myself together to stop myself being in floods of tears that day, and I just about managed it.
"But whatever the future holds, I am certain that Clive and all us here at Ditcheat will reflect on a magnificent past and I am sure we will both go on searching for the unattainable in the future.
"Namely, a horse to replace the irreplaceable legend that was, and is, Kauto Star."
Mick Fitzgerald partnered Kauto Star just once but he was lucky enough to be aboard when the Village Star gelding won his first Grade One in the 2005 Tingle Creek.
He said: "He's just been an amazing horse.
"It was a pleasure to be asked to ride him in the Tingle Creek and a treat to do so.
"I actually went down to Ditcheat last week to do a piece for At The Races and I saw Kauto and he looked absolutely fantastic.
"It's great news he's been retired as he can now go and enjoy the rest of his life.
"He's produced some incredible performances. Haydock last year was fantastic and all you had to do was look at Paul Nicholls after the race and you could see what the horse meant to him.
"I think Paul has done an absolutely incredible job with the horse. He's an amazing trainer and he deserves a huge amount of credit.
"You'd have to say Kauto Star is right up there with the best (there's ever been).
"To win two Tingle Creeks, two Gold Cups and five King Georges says everything you need to know. He's been an amazing, amazing horse."
Jockey Sam Thomas, who won the 2008 Cheltenham Gold Cup aboard Denman, partnered Kauto Star to glory in the 2007 Betfair Chase at Haydock.
He said: "I was lucky enough to ride him and win on him and he has been a very special horse.
"He did an enormous amount to raise the profile of National Hunt racing and I think enormous credit has to go to Paul Nicholls for producing to win all those big races on the big days.
"To win two Gold Cups, Tingle Creeks and five King Georges is incredible and he might not have done that had he been trained by anyone else.
"It's a shame we won't see him run again but at least he will be able to enjoy his retirement with his old friend Denman.
"I think Kauto's record will struggle to be beaten in my generation and now he's retired, along with Denman, it's the end of an era.
"The battles between the two of them were a big part of my career and part of my life that I'll never forget.
"Kauto was a wonder horse and we might not see the likes of him and Denman again."