Charley Hoffman carded a blemish free 67 to take a one-shot lead after the first round of the Valero Texas Open on a day when the wind played havoc in San Antonio.
Hoffman was one of just 12 players to record an under-par round on Thursday as many struggled with two-time major winner Martin Kaymer firing a 10-over-par 82.
It was also a disappointing day for Graeme McDowell who was forced to withdraw from the tournament with an ankle injury.
The Northern Irishman suffered the problem during practice on Wednesday and, although he managed to play his opening nine holes on Thursday, he pulled out of the tournament before setting his sights on getting fit for the Masters which begins on April 9.
McDowell, tweeted: "Apologies to everyone at @valerotxopen for my withdrawal. Strained my lower left leg/ankle area practicing y/day and played with heavy strapping on it in the pro am and this morning.
"With The Masters upcoming I decided that getting fit is imperative. Don't like WDs.
"The week here at @valerotxopen had everything I wanted. Great people and great course. Disappointed this has happened. Thanks to everyone."
Back out on the course, Hoffman took advantage of calmer winds in the afternoon to record five birdies and finish the day a shot clear of Australia's Aaron Baddeley.
The American picked up shots on the second, third, ninth, 11th and 17th to post the round of the day but the shot of the day undoubtedly belonged to the man a shot behind him.
With the wind behind him on the 336-yard par-four 17th, Baddeley took on the green but missed left and had to go back to the tee after finding an unplayable lie.
That presented the 34-year-old with no problem, though, as he holed what was his third shot to record an improbable birdie.
That had put him in the lead at the time following birdies on the first, second, eighth and 15th and a single bogey on seven but Hoffman overhauled him.
A birdie-birdie finish from Max Homa saw him move into third a further shot back as he overcame a poor start.
The 24-year-old dropped shots at one and five but birdies at six and eight saw him reach the turn level and four birdies and a single bogey on the back nine catapulted him into contention.
Phil Mickelson also had a birdie-birdie finish to get to two under alongside Ryan Palmer after a broken club had briefly contributed to him slipping over par on the back nine.
The five-time major winner reached the turn one under after a bogey and two birdies and dropped a shot on 10 before putting his tee shot on 12 into a bunker.
His club head then snapped off the shaft upon impact as he played his bunker shot and he dropped a further shot before birdies on 14, 17 and 18 saw him finish strongly.
There was then a group of seven players at one under including Jordan Spieth, Jimmy Walker and Zach Johnson.