AP McCoy says he will probably quit immediately if he wins the Grand National at Aintree on 11 April.
The 19-time champion jockey told Channel Four Racing he would be likely to "stop there and then".
McCoy, 40, has told the BBC he could wait until two days before the big race to decide which horse he will ride for owner JP McManus in his final National.
The Northern Irishman has been linked with favourite Shutthefrontdoor, but Cause Of Causes is an alternative.
He finally won the National for the first time, at the 15th attempt, on Don't Push It in 2010.
McCoy, on the verge of becoming champion jockey for the 20th consecutive year, announced last month he would retire by the end of the jump racing season, which concludes in Britain at Sandown on 25 April.
He has been heavily linked with the Jonjo O'Neill-trained 8-1 favourite Shutthefrontdoor for the National.
"I think I'm riding Shutthefrontdoor, but Cause Of Causes won at Cheltenham, so he has a good chance now," he told BBC Sport.
McCoy added: "Shutthefrontdoor or Cause Of Causes, it will be one of them.
"Winning the Gold Cup at Cheltenham is the pinnacle of your sport - the race everyone wants to win, but the Grand National is the most famous race in the world. It's definitely nice to have won it. I'd love to do it again."
|McCoy still racking up the winners|
|AP McCoy's only Grand National success came in 2010 with Don't Push It, owned by JP McManus and trained by Jonjo O'Neill, helping him become BBC Sports Personality of the Year. He is set to win the title of National Hunt champion jockey for the 20th straight year, having so far ridden 224 winners this season.|
When asked whether he would retire if victorious in this year's race, he told Channel Four Racing: "I think it will probably be the right thing to do.
"I think I'll probably stop there and then."
The chance he could ride last year's Irish National winner Shutthefrontdoor has led to bookmakers suggesting it could go off the shortest-priced National favourite since Red Rum in the 1970s.
Cause Of Causes gave owner McManus a 64th birthday present when opening his account over fences in the National Hunt Chase on the first day of the 2015 Cheltenham Festival.
The seven-year-old, trained by Gordon Elliott in Ireland, is now rated a 25-1 shot for Aintree, fifth in the betting behind Shutthefrontdoor - whose two wins this season have come with Barry Geraghty in the saddle - and last year's winner, the Worcestershire-trained Pineau De Re.