UPDATE 1:00 PM ET: Little known Joost Luiten of the Netherlands was the leader through 11 holes at the PGA Championship.
Luiten, who picked up his first career European Tour victory last year, was at 6-under par thanks to four birdies and an eagle.
The trio of Gary Woodland, Rory McIlroy and Carl Pettersson were all a shot back. Woodland had back to back birdies on Nos. 7 and 8 as he was nearing the end of his round while McIlroy was working on a birdie-free round through 16 holes. Pettersson as well was bogey-free through 13 holes.
Pat Perez was the clubhouse leader after posting an opening round of 3-under 69 in ideal conditions for the morning starters.
Tiger Woods picked up a third bogey on his 13th hole of the day to fall to 2-under par, tied with playing partner and defending champion Keegan Bradley.
Weather forecasts predicted a mix of sunny and cloudy conditions, along with heat and humidity, for the rest of Thursday with a chance of thunderstorms in the late afternoon.