As a human and a golfer, Bubba Watson said he can't help but allow negative thoughts to cross his mind.
He hasn't played the 18th hole at Whistling Straits since he followed a birdie on the opening hole of a playoff in 2010 by splashing his six iron into the water in the PGA Championship at this very course.
"I did everything I was supposed to do, but one person beat me. Coming back here, I've got good memories," Watson said after warming up with a nine-hole practice round Tuesday because of a fishing date with his son.
Watson is paying attention to course changes, and putting the one swing five years ago behind him.
"The rough is thick and healthy," Watson said. "I haven't seen greens runs this well in a long time."
Watson was runner-up in 2010 in a playoff with Martin Kaymer at Whistling Straits just weeks removed from his first ever PGA victory. Watson finished second in back-to-back tournaments entering Thursday's first round.
"The week (in 2010) was good, only one person beat me," Watson said. "Tough golf course. I remember the golf course being tough. ... Just like this week, if you don't hit the fairway, it's going to be tough. Especially that front nine."
Whistling Straits, host of the 97th PGA Championship, is the third links style golf course in four PGA majors this season. Watson missed the cut at the U.S. Open and British Open. He tees off Thursday at 8:45 a.m. ET (Jim Furyk, Paul Casey).
Tiger Woods is only a few groups behind (9:15 p.m. ET) and spent most of the morning on the driving range with a driver in his hand. Woods showed some signs of frustration during the session but arrives in Wisconsin following a positive showing two weeks ago at Greenbrier. He'll be participating in his 18th career PGA Championship.
Other than thick mosquito swarms, Woods described the 2015 setup as favorable. After seven years without a major, Woods wouldn't say he has "lost a step."
"I can still walk the same pace on the golf course," Woods said with a smile. "Relatively speaking - I'm longer now than yardage than I was earlier in my career. Compared to other players I'm not. My understanding of the game has gotten much better. My knowledge of golf courses and different types of venues has gotten better."
Woods has missed the cut in his past two major starts. He said distance will be critical, accuracy moreso, and figuring out tricky short holes essential. Woods would love the chance to hoist another major championship trophy.
"It's pretty heavy, especially when you're tired," Woods said.
Woods said stamina will be a challenge for top-ranked golfer Rory McIlroy this week, recalling playing nine months on a bum knee and battling back issues that required surgery.
McIlroy walked the course again Tuesday and then hit the driving range. He plans to play in his first event since being sidelined by an ankle injury on July 4. European Ryder Cup captain Darren Clarke, who advised McIlroy against playing, said there's only one reason McIlroy would play.
"He's the world No. 1, and he's done many amazing things in his career," Clarke said. "I wouldn't be surprised to see him in contention this week."
NOTES: Clarke and 2016 U.S. Ryder Cup captain Davis Love III (1:20 p.m. ET) are paired together in the first two rounds. Clarke said he will play a limited schedule next year, focusing on his Ryder Cup duties, including attending multiple tournaments in which he will not participate. ... Whistling Straits will host the 2020 Ryder Cup.