Tom Watson walked up the 18th fairway last year as the oldest champion in the 52-year history of the Colonial. Unless another plaid jacket is waiting for him this time, he'll walk away from the PGA Tour for good.

He turns 50 in September, and the Senior Tour beckons. The way Watson has been playing lately, he has his hand cupped to his ear.

"I can make the statement now that I'm going to take most of the rest of year off and prepare for the Senior Tour," Watson said. "At this point, this will be the last tournament I'll play on the regular PGA Tour."

He will still play the U.S. Open next month. He plans to be in Scotland in July, when the British Open returns to Carnoustie for the first time since Watson won his first claret jug in 1975. He would like one more shot at the PGA Championship, the one major that has kept him from the career Grand Slam, but would need a special exemption.

He could always change his mind.

When asked whether he would continue to play against guys nearly half his age if he were to win this week in the Mastercard Colonial or at least put a scare into somebody on Sunday, he flashed that famous gap between his front teeth and replied, "Of course."

There's no reason to believe that will happen.

Watson hasn't scared anyone this year. His best finish was a tie for 16th in the Sony Open. He has missed his last three cuts and has a scoring average of 73.22

His iron play, the hallmark of a Hall of Fame career that includes eight major championships, is in the worst shape since he can remember. His putting isn't getting any better, either.

"If I had won a couple of tournaments already or was in the top 20 money winners, boy, it would be difficult to go out on the Senior Tour," he said. "But it's easy to talk about it right now."

Watson is part of a tantalising threesome expected to inject some life into the Senior Tour. Tom Kite and Lanny Wadkins, with whom he spent the better part of three decades doing battle on the PGA Tour, will turn 50 in December.

He knows the competition won't be nearly as stiff as what he faces this week against the likes of Davis Love III, Steve Elkington, Fred Couples, Justin Leonard or Phil Mickelson.

Still, he looks forward to seeing new courses and beating old friends.

"I make no bones about it, winning on the PGA Tour is the ultimate challenge," he said. "Winning anywhere is a challenge, but you obviously want to win against the strongest fields you can play against because it means you've beaten the best. But I still love to compete."

Watson hasn't been able to do that lately. All that's left is a ceremonial stroll up the 18th fairway -- usually on a Friday -- knowing that it may be the last time he plays Bay Hill or the Byron Nelson or Colonial.

Watson felt sentimental last week at Las Colinas, especially since Nelson has been his longtime mentor. He needed a birdie on the 18th hole Friday to make the cut, but instead three-putted from the fringe for a 41 on the back nine.

"I love Byron's tournament and I hope to be back there, but I'm not sure I will be," he said. "Walking up the last hole was somewhat sentimental to me, as it has been in most of the tournaments I've played in this year."

His 23rd trip around Colonial Country Club will look slightly different. The course has 34 new trees, most of them 25 feet high. The biggest change Watson expects is how firm and fast Colonial could play.

"Last year, it played the easiest I've seen it," he said.

Watson finished at 15-under 265 for a two-stroke victory over Jim Furyk. It was all made possible by one of the most remarkable shots of his career, perhaps a notch below his chip-in at Pebble Beach to win the 1982 U.S. Open or his 2-iron into the 18th green at Royal Birkdale to secure the 1983 Open.

With an off-balance stance from the fairway bunker on No. 9, Watson hit an 8-iron through wind and over water to 10 feet and made the birdie putt.

When Watson thinks about that bunker shot and finally winning in "Hogan's Alley," he realises that he happened to be playing pretty well that week.

With the Senior Tour only four months away, that's not the case right now.