Charles Howell III fired a bogey-free five-under-par 67 to open up a one-stroke lead after the third round of the AT&T Classic.
Howell started with five pars before picking up back-to-back birdies before adding three more birdies on the back nine to claim the lead heading into the final round for the fourth time in his career.
Kenny Perry capped a third round 69 with a birdie at the last to move onto 12-under-par to remain second, while overnight leader Jonathan Byrd slipped to third alongside David Toms (69) and Ryan Palmer (70) at 11-under following a one-over 73.
"I gave myself a lot of opportunities," said Howell. "I played fairly conservative into the greens. I drove the ball well and got in places where I could play from. Not losing any shots off the tee is big, especially around this course.
"There is some strategy and thought off the tees as well as into the greens. That's why I think it's so important to get the ball in play off the tee."
Perry looked to have handed Howell a little more breathing room heading into Sunday after bogeying 16, but made and up-and-down from the back bunker at the last for a closing birdie to complete a round which also included two further birdies, an eagle and another bogey.
"It was a good day. I hit the ball beautifully and got off to a good start," said Perry. "I felt very comfortable. I wasn't nervous and my swing felt great."