Brian Davis hits second 65 to share the lead in Texas

Davis, who was third on 11-under-par at the halfway stage, was five under for the second day in a row to be level with Bryce Molder at the top of the leaderboard.

The 35-year-old, in a run of poor form heading into this million-dollar event, has not won on the PGA Tour but was aiming to keep his nerve in the final round after a bogey-free two days.

"I wasn't playing that bad but I just wasn't putting it all together," Davis said, after totalling just 22 putts for his round. "Obviously this week has been a turnaround and I am in contention so I am really happy."

He added: "I'd lost my focus. Missing three cuts in a row, I wasn't exactly happy coming in. I've had to adjust my thinking a little bit. Not everybody can play well every week. You have to take the rough with the smooth sometimes."

After an impressive 64, Zach Johnson was a shot off the leaders while first-round joint leaders Jeff Overton and Jason Bohn, with 66 and 68 respectively, were alongside Ben Crane (64) at 14-under.

England's Paul Casey and Martin Laird of Scotland were in a group tied for 28th, at eight under, after strong rounds of 66.

KJ Choi earlier came within one hole of an extraordinary third round before his day was ruined by a quadruple bogey at the 18th. After seven birdies and an eagle, Choi was on target for an eight-under round of 62 before he hit trouble on the final hole.

His tee shot went left, he found the water with his third, then skidded past the green with his sixth, before eventually putting from eight yards to sign for a 66. A par on the last would have put him firmly in contention on 14-under for the weekend.