Dustin Johnson continued his fine first round form in Major Championships as he claimed a one shot lead after day one of the US PGA Championship at Whistling Straits.
The American led after 18 holes at the US Open Championship and the Open Championship earlier this summer but could not convert either of those positions into victories as he continues to search for a first Major title.
The last time the US PGA Championship was held at Whistling Straits in 2010, Johnson was one shot ahead with one to play and thought his bogey on the 18th meant he would be heading into a play-off with Martin Kaymer and Bubba Watson.
However, the 31-year-old was then penalised two strokes after it was ruled he had grounded his club in a fairway bunker before hitting his second shot.
Johnson had also lost a three shot lead in the final round of the US Open two months earlier and he three putted the 72nd hole at Chambers Bay this year to finish a shot behind Jordan Spieth.
He will take a one shot lead over Swede David Lingmerth into the second day here with an eight-strong group including playing partner Jason Day and Matt Kuchar a further shot back.
Johnson carded an eagle, five birdies and a solitary bogey in the morning before the wind began to pick up and the World Number Eight admitted he felt it was easy for him to record the 66 which catapulted him to the top of the leaderboard.
"Today was pretty easy, I would have to say," Johnson said. "I was swinging well and I was hitting the shots where I was looking and I really felt like I was just super patient, stayed focused all day.
"I played pretty well at the US Open on the weekend. At the British Open I didn't play well on the weekend, but even the first two days I didn't feel like I was playing that good golf. I wasn't too comfortable with my swing. I wasn't hitting the shots that I wanted to hit. I didn't feel like I was too much in control.
"Today, I really felt like I had my ball under control a lot like I did at the US Open. We'll just have to see what happens. It's only the first round, we've still got a lot of golf to play."
Thomas Bjørn, Justin Rose and US PGA Championship debutant James Morrison were in the group at three under and Morrison was revelling in his first taste of the year's final Major.
He started the year 361st in the world rankings but earned his place in the field thanks to winning the Open de España and finishing second in the Alstom Open de France in Paris.
That also earned him a place in last month's Open Championship where he finished in a tie for 20th and he now feels he is mentally prepared for Major Championships.
"It's about how good you are in the brain, how strong you are and how much you want to achieve it," he said. "I love competing, I love being in the mix and I really enjoy it and there comes a point where you've got to man up and get on with it and I'm doing that, hopefully.
"It's nice to come here and play another Major after playing the Open a few weeks ago. It's an amazing golf course.
"I've been playing well so I'm kind of carrying on, really."
Bjørn had held the outright lead after five birdies in his first 12 holes but, despite finishing with two bogeys, he was pleased with his day's work.
"It's disappointing obviously to finish with two bogeys but I came into the week not playing very well," Bjørn said.
"I played poorly last week and worked very hard early in the week and you're never really sure where you are but I was really, really pleased with the way I played for 16 holes.
"A couple of little shots (were lost) at the end but they'll not destroy a pretty good day."
Kaymer, who won the tournament here in 2010, was four under walking up the ninth, his last, but registered a double bogey to drop to two under and Anirban Lahiri finished on the same score after a double on 18.
Emiliano Grillo was also in the group at two under on his Major debut after firing six birdies and four pars while Marcel Siem also carded a 70.
Defending champion and World Number One Rory McIlroy was in the group at one under alongside Spieth, Branden Grace and Francesco Molinari.
Sergio Garcia, Lee Westwood, Louis Oosthuizen, Mikko Ilonen, Marc Warren, Luke Donald, Kiradech Aphibarnrat and Bernd Wiesberger were all at level par alongside Søren Kjeldsen, who was playing in his 500th European Tour event.
