Kevin Na overcame a double-bogey seven to take a two-shot lead into the final round of the Charles Schwab Challenge.
The 35-year-old, looking for his third PGA Tour title, carded a one-under 69 to go clear on nine under at Colonial Country Club near Fort Worth after overnight leader Jonas Blixt slipped back after a 74.
However, Na's round would have been better had he not thinned a bunker shot from the greenside sand at the 11th after being distracted by a spectators' phone ringing and then duffed his chip back.
"I played solid the whole front nine and after a double-bogey I grouped it together," he told Sky Sports.
"If I shoot a few under par I should stay ahead of the other guys and I should be all right."
There are 14 players within five shots of the lead with Jordan Spieth - who looked like he was returning to form at last week's US PGA Championship - lurking ominously in the group in a tie for second on seven under after he shot a 68.
Blixt, at five under, is still not out of it but four bogeys and no birdies saw him surrender his 36-hole advantage.
Former Ryder Cup captain Jim Furyk, at 49, is also just two back after a round of 68.
