Will Zalatoris took advantage of the friendlier conditions later on Friday to finish his round five under, giving him the outright lead at nine under through two rounds at Southern Hills Country Club.
He is the only player to shoot 66 or better in the first two rounds as fellow fast-starters Rory McIlroy and Tom Hoge both finished over par their second time around the course.
Zalatoris went bogey-free, birdieing the first hole, the 17th, and three consecutive starting on the 11th. While the conditions were conducive to scoring, both of his playing partners – Cameron Smith and Victor Hovland – shot even-par 70s.
In outright second place at eight under is Chile's Mito Pereira, who was one shot off the round-of-the-day with his six-under 64, leaving him at eight under through two rounds. He had seven birdies – including back-to-backs on holes four-five and 10-11 – and just one bogey on 12.
Justin Thomas posted his second consecutive 67 to have a share of third place at six under, and he is one shot ahead of Bubba Watson, who shot Friday's best round of 63 – tying the course record – with nine birdies and two bogeys. He sits alone in fourth.
Tiger Woods was in danger of missing the cut after a double-bogey on the 11th moved his score to five over, but he responded in terrific fashion.
Showing his quality, Woods one-putted on the next six greens for two birdies and four pars to leave him one shot inside the cut-line (four under) heading onto the 18th. With a par on the last, he finished his round one under and earned two more rounds of action.
First-round leader McIlroy is in a share for fifth af four under after his round of 71, and he's tied with Mexico's Abraham Ancer and America's Davis Riley.
England's Matt Fitzpatrick and American Stewart Cink are one further shot back at three under in a tie for eighth, and there is a logjam at two under, tied for 10th, highlighted by Cameron Smith, Tyrrell Hatton and Matt Kuchar.
A strong grouping of Xander Schauffele, Tony Finau and Jordan Spieth are part of a large contingent at one over, with Brooks Koepka and Jon Rahm a further stroke back after they posted scores of 67 and 69 respectively on Friday.
Jason Day is tied with Woods at three under, while at four under Collin Morikawa and Hideki Matsuyama just did enough to qualify for the weekend.