South African Branden Grace had seven birdies in a six-under par 66 on Thursday to take a one-stroke lead after the first round of the US PGA Tour's Texas Open.
Grace, coming off an 11th place finish in his title defence at the Heritage, birdied three of the four par-fives on the TPC San Antonio Oaks Course.
His birdie at the par-five eighth marked the start of three birdies in a row, a burst that included a 25 foot putt at the ninth to salvage a birdie after his tee shot found the rough.
"I hit it right in the thick of stuff and managed to get a flyer," Grace said. "I think I hit a wedge from 180 yards, got it to the back level. Made 25-footer for birdie. That's the best birdie I made all day."
Grace played early and said the winds that can bedevil golfers at the Oaks were mild.
"There's gusting," added Grace. "The nice thing about this place, there's not that many trees out there. It's all more bushes.
"So you can pretty much judge what the wind is going to do to the ball as soon as it gets over them. It was nice. This is a nice little breeze to what it could be out here."
Will MacKenzie, John Huh, Steven Alker and Stewart Cink shared second on 67. Huh had five birdies without a bogey in his five-under effort.
MacKenzie opened with a bogey at the 10th but had six birdies the rest of the way.
"That was a tough start, but then I started hitting some good iron shots in there and made some clutch putts," he said. "The second hole I hit a sprinkler head in the middle of the fairway -- goes into the lip of the bunker and I made a pretty miraculous birdie there."
New Zealand's Alker joined the group with birdies at his last three holes.
Cink teed off on 10, and after two birdies and a bogey in his first nine he really got going with three straight birdies at the second, third and fourth. He added one more at the sixth, hitting just eight of 14 fairways in regulation but finding 15 greens.
"It was mostly my iron play," said Cink, who hasn't won since his 2009 British Open triumph. "I hit a lot of really nice iron shots and hit the ball the right distance."
It was a further stroke back to a big group on 68 that included former US Open champion Graeme McDowell of Northern Ireland, Brooks Koepka and South Korean Noh Seung-Yul. Ken Duke was also at four-under after a round that included holing out from a bunker for an eagle at 14.
Defending champion Charley Hoffman carded a 71, while Curtis Luck, the 2016 US Amateur champion from Australia who is making his professional debut, signed for a 73.
Luck opened with three straight bogeys. He finished with six bogeys, three birdies and an eagle.