Jack Nicklaus says what Tiger Woods has achieved in holding all four major titles at one time will probably never be repeated.

"What he has done nobody has ever done, and it is unlikely that anyone will do it again," Nicklaus, who has won more career majors than anyone else, said on his personal website yesterday.

"What Tiger has done is the most remarkable feat, not only in golf but probably in all of sports."

Woods's victory in the US Masters last Sunday gave him a record fourth professional major in a row, following the US Open, British Open and PGA Championship titles he won last year.

But many traditional followers of the game contend that a true grand slam has to be achieved within a calendar year. Nicklaus, who won a record 18 career majors between 1962 and 1986, argues that this debate is irrelevant.

"The question keeps being asked of me: is it a grand slam? I don't think it makes a difference. By the definition of a grand slam, no it's not. But, what it's called is irrelevant.

"What he's done is what matters most, and what he's done is unbelievable. I call it the most remarkable feat I have ever seen or heard of in golf."

Byron Nelson (89), who won 11 straight PGA Tour events in 1945, has also acknowledged Woods's feat as being golf's finest achievement.

Nelson, who hit the ceremonial first shot at the Masters for the final time last week, said on the PGA Tour website: "I put it absolutely at the very top." He added: "He may win the rest of them this year. I'm very proud of what I did, but I think this (what Woods has done) is most unusual."