Tom Watson fears fellow American golf great Tiger Woods may not be the same player ever again if his compatriot is forced into replacement knee surgery.
Watson was speaking two days out from the start of the British Open - an event he was won five times - here at Royal St Georges's, which will represent the second straight major championship that Woods has missed.
Woods, 35, has not played competitively since limping out of the Players Championship in Florida on May 12 and there has been speculation the winner of 14 majors may not play again this year - or even retire completely.
Watson, now 61, stunned the sporting world two years ago when he was a putt away from winning a record-equalling sixth Claret Jug at Turnberry in Scotland, having had a hip replacement operation, only to lose that year's British Open to fellow American Stuart Cink in a playoff.
However, Watson said there was a significant difference between his injury and the problem confronting Woods.
"With a hip you put a new one in and here we go," he told reporters in his role as an ambassador for MasterCard at Royal St George's on Tuesday. "The knee takes a lot more stress - it's out there on its lonesome and rotates.
"Whether he (Woods) is going to have a total knee replacement who knows, but that may be a more difficult thing to come back from if he does.
"The most important thing is for him to get well so he can put the force on it that he has to for his swing. He loves to work out, but can it be put back in shape is the question - that's the concern - and whether it's
going to prevent him from dominating the game again who knows.
"Nobody has ever dominated the game like he has," added Watson, who enjoyed a thrilling rivalry with compatriot Jack Nicklaus, the man whose record of 18 major titles Woods is chasing, towards the end of the 1970s.