Tom Lehman is having one heck of a season for a guy who feels his swing has been out of whack.

Lehman leads the Champions Tour in earnings, tops the Charles Schwab Cup standings and will try for his fourth victory in nine starts when he tees off Friday in the Principal Charity Classic.

But in Lehman's mind, something isn't quite right with his game and last weekend was a reminder. The 52-year-old Minnesota native ran off six straight birdies in the third round of the Senior PGA Championship at Valhalla, the longest such stretch on the tour this year, then struggled to a final round 77 that included two double-bogeys.

"I could feel that round coming," Lehman said. "The last several rounds I've played have not been very good. I have been very erratic. My swing has been a little bit out of synch. I would play really well for a number of holes and I would play really poorly for a number of holes."

Lehman said his up-and-down play goes back to his victory in the Regions Tradition at Birmingham in early May, the senior tour's first major.

"I could feel my swing was getting away from me," he said. "I wasn't hitting it the way I normally do. I didn't make many bogeys, so I kind of won that one by just not beating myself. But at the PGA Championship, I hit some great shots and I hit some really poor shots and I just never ever got into a flow where I played well for 18 holes."

Lehman has seen clues this week that his game might coming back around. He could have played in the Memorial, but thought he'd be better served at this point by playing the par-71 Glen Oaks course.

The course has been receptive to low scores — Nick Price won last year at 14-under — but wind can turn the layout into a far more daunting challenge. Breezy conditions are forecast for Friday, with gusts up to 30 mph.

"I'm way better today than I was last week," Lehman said after his Thursday pro-am round. "I actually saw a swing that I made (last week) and no wonder I hit it so lousy. That was terrible. So I kind of had an idea of what the deal was and how to fix it.

"To me, it's about rhythm and balance. I felt way better today than I did Tuesday and way better Tuesday than I did Sunday."

Lehman's fast start has made him the leading contender for the tour's player of the year award, an honor that would give him a trifecta if it happens. He also has been player of the year on the PGA Tour (1996) and Nationwide Tour (1991).

No one has been player of the year on all three tours. Then again, not everyone has played on all three tours.

"You have to be, I wouldn't say lousy enough, but you have to struggle enough at some point to be able to have a chance to win on the Nationwide," Lehman said. "A lot of guys are just too good to ever have played there. Unfortunately, I wasn't, but it sure was good for me."

The Senior PGA, won by Tom Watson, was the fourth straight Champions Tour tournament that ended in a playoff. Such a string has occurred only once before, in 2005.

"It just goes to show you there's a lot of guys on an even scale out here," said Mark Calcavecchia, who led at the Regions Tradition well into the final round. "You've got to putt good. You've got to have a good week on the greens because if you don't, other guys will. Nobody's ever won a tournament without making a bunch of putts and getting lucky."

Calcavecchia's lead in Alabama evaporated with a double-bogey on No. 12 and he closed with a 75 to finish in a tie for fifth. He also finished fifth at The ACE Group Classic in February. The 1989 British Open champion is still looking for his first victory in just under 12 months on the 50-and-over tour.

"I've had some good chances to win and haven't quite pulled it off yet," he said. "I knew the golf was great because I've been paying attention to the scores. But it's better than I even thought it was. Some guys are better now than they ever were in their whole careers."

John Huston, a seven-time winner on the PGA Tour, will find out how he stacks up against the seniors when he makes his Champions Tour debut on Friday. Huston, whose last victory came in 2003, turned 50 on Wednesday and was treated to a birthday cake in the clubhouse after his pro-am round.

"From the start of the year, when I knew when it would be, where it would fall, I was looking forward to it," Huston said. "I'll try not to put too much pressure on myself to do whatever and just see how it works out."

Also playing in his first Champions event: Damon Green, best known as Zach Johnson's caddy on the PGA Tour.

Fifteen players have won in their Champions Tour debut. The last to do it was Tom Pernice Jr. at the 2009 SAS Championship. Pernice, who's playing this weekend, has not won in 18 tournaments since that memorable start.