Zach Johnson, seeking his first victory since the 2015 British Open, closed with a six-foot birdie putt to seize a share of the lead Saturday at the PGA Texas Open.
The 42-year-old American fired a four-under par 68 third round to match compatriot Andrew Landry on 13-under 203 after 54 holes at TPC San Antonio.
Trey Mullinax fired a course-record 62 to stand third on 204, one stroke in front of fellow American Ryan Moore with Scotland's Martin Laird and Americans Jimmy Walker, Chris Kirk and Sean O'Hair sharing fifth on 207.
"Obviously I don't think you ever walk onto a tee and think 62," Mullinax said. "But I thought I had some low rounds in me. I thought I was rolling the ball well and felt really good with my irons on the range this morning, so got some stuff to happen."
Johnson, who won his first major at the 2007 Masters, seeks his 13th career PGA title and third Texas Open victory after 2008 and 2009 at LaCantera Golf Club, where he shared the course record of 60.
He marveled at Mullinax's new TPC mark, saying, "62 is ridiculous but you can see it."
"I could see a guy that hits it hard, which he does. I could see that because the par-5s kind of become par 4s to some degree with this south wind. And you've still got to hit good shots and putt."
Mullinax's record run began with birdies on three of the first four holes, putts of 11 feet at the first, 13 feet at the third at 17 feet at the fourth. He opened the back nine with a seven-foot birdie, took his lone bogey at the 11th and responded with a 14-foot birdie putt at the 12th.
Then came the fireworks.
Mullinax holed out from 95 feet for eagle at the par-5 14th, sank a 40-foot birdie putt at the par-3 16th and a six-foot birdie putt at 17, then reached the 18th green in two and holed a 16-footer for another eagle and the course record.
Laird had his own long-range eagle to pull into contention, sinking an 83-foot eagle putt at the par-5 eighth.
After two birdies and two bogeys on the front nine, Johnson caught fire on the back side, sinking 20-foot birdie putts at the par-4 11th and 15th holes and a 17-foot birdie putt at the par-5 14th as well as his closer at the par-5 18th.
Landry, seeking his first PGA title after a January playoff loss to Spaniard Jon Rahm in the California desert, fired a bogey-free 67 to match Johnson atop the leaderboard.
Landry sank a six-foot birdie putt at the third, a seven-footer at the fifth and dropped his approach inches from the cup for a tap-in birdie at the sixth. He added an eight-foot birdie putt at the par-3 16th and put his approach two feet from the cup at 17 to set up a final birdie.