JB Holmes carded a four-under par 68 to tie for the lead with Harris English at the Farmers Insurance Open at Torrey Pines.
The 2008 Ryder Cup winner picked up a shot at the fourth and, after a bogey at the very next hole, found two more birdies to reach the turn in 34.
Holmes sunk three more birdies at the 10th, 13th and 14th, but dropped two strokes in the final four holes as he finished the day on nine-under par alongside English, who carded a one-over round of 73.
However, the leaders may have company on the final day as the top 15 players on the leaderboard are separated by just three strokes.
Among them is Australian Jason Day, who holed his iron shot to the 17th on his way to a 71.