Davis and Oosthuizen both finished 36 holes over the Redstone Golf Club at 11-under 133 and had a one-shot lead when play was halted by darkness. There was golf played from dawn to dark Friday after the first round was halted by rain Thursday with only half the field having finished.
Davis and Oosthuizen were among those who went out early Friday to complete the first round and they then played their entire second round as well.
Jeff Maggert was alone in third at 10-under, but he had eight holes left to play and could wind up with the second-round lead.
Those at 9-under 135 included Tommy Gainey, Greg Owen, J.B. Holmes and defending champion Phil Mickelson, who completed only three holes of his first round Thursday and then got hot early Friday on his way to a 65 that put him in a three-way tie for the lead after 18 holes.
Mickelson shot a 70 in the second round, finishing up at the par-3 ninth by missing a 6-foot par putt.
Angel Cabrera and Carl Pettersson, who shared the first-round lead with Mickelson, had late tee times Friday and failed to capitalize on easy scoring conditions. Cabrera was only 1-under through eight holes of his second round and was three shots off the pace. Pettersson was even par through eight holes and was four shots back.
The winner of each PGA Tour event earns an invitation to the Masters and this is the last tournament prior to the big show next week in Augusta, Ga. Davis is not currently eligible to compete at the Masters. He has two European Tour wins to his credit, but none since 2004.