American Jim Herman fired a five-under-par 67 to go joint top of the leaderboard and put himself in contention for a maiden PGA Tour title after the third round of the Shell Houston Open.
Herman struck five birdies in a blemish-free round that takes him to the summit on 11-under for the tournament, a climb of seven places from the halfway point.
"I am very pleased with my play, I kept in the fairway and I had a good look at the tucked pins," he told the PGA Tour website.
"I put myself in good positions with some uphill putts and I was able to make a few.
"There's a lot to play for tomorrow, but I am not going to worry about that I am just going to keep doing what I have been doing over the last three days."
Herman is joined at the top of the leaderboard by Jamie Lovemark, who started the day one shot off the lead, after his round of 70 which contained two birdies and two bogeys.
There are three men tied one shot behind on 10-under, with Henrik Stenson, Russell Henley and Dustin Johnson all in contention on the final day, though overnight leader Charley Hoffman enjoyed a less successful day as his two-over-par 74 saw him slip down to eight-under.
Rickie Fowler will be eyeing a final-round charge as a 70 moved him to seven-under, while Jordan Spieth also carded a 70 and is on six-under.
Martin Laird is the highest-placed Brit, but his three-over-par 75 saw him slip well off the pace at two-under.
