Gary Woodland shot a bogey-free, 6-under-par 65 to surge into the lead as the U.S. Open reached the midway point after Friday's second round on the shores of Pebble Beach, California.
Woodland carries a 9-under mark into the weekend, holding a two-shot edge on England's Justin Rose, who held the lead for most of the day after his 70 until Woodland's late-day charge.
Woodland, who started on the back nine, closed with a birdie putt of about 50 feet on the ninth hole.
South Africa's Louis Oosthuizen became the co-leader briefly before settling for a 70 that put him in third place at 6 under.
Oosthuizen had a bizarre final nine holes, bogeying four holes and birdieing four others. His only par on the back nine came at No. 9.
Aaron Wise (71) and Northern Ireland's Rory McIlroy (69) share fourth place at 5 under.
Rose had three birdies and two bogeys on Friday. He shot a blistering 65 in the opening round.
"I'm happy. I felt there was an opportunity to go a few better," Rose told Fox Sports 1 after his round "You're going to make some mistakes during the course of the week. You shake it off, and that's what U.S. Opens are all about."
McIlroy appeared positioned to bolt to the lead, but he bogeyed No. 13 and took a double bogey on the par-5 14th hole. McIlroy regrouped with birdies on the next two holes.
Wise, who fired a first-round 66, had consistency issues while carding a 71.
Wise had five birdies, three bogeys and a double bogey.
"I was able to stay patient, wait for the birdies to come to me," Wise said. "And (No.) 17 was a huge birdie, and to get one on 18 and finish even for the day makes me feel good."
Two-time defending champion Brooks Koepka is five shots off the pace after his second straight 69. He is the first defending champ since Scott Simpson in 1988 to score under 70 in his first two rounds.
Koepka had three birdies and one bogey while hitting 12 of 14 fairways. He did experience some putting issues.
"Funny thing was I was hitting good putts," Koepka told Fox Sports 1 after his round. "I don't mind it if I'm going to hit good putts and they're going to miss. That happened today. Ball-striking was tremendously better today. ... Never really felt like I had to work. It was quite an easy round."
Also tied with Koepka at 4 under are Matt Kuchar (69), Chesson Hadley (70) and Chez Reavie (70). Kuchar made an eagle putt on No. 18 to end his round.
Tiger Woods bogeyed his final two holes -- at Nos. 8 and 9 -- to post a 72. He sits at even par for the tournament, nine strokes behind Woodland.
"I'm a little hot right now," Woods said, perturbed by how he capped the round.
Woods also had a positive perspective halfway through the tournament.
"Right now I'm still in the ballgame," he said. "There's so many guys with a chance to win. We've got a long way to go."
Xander Schauffele, who shot 66 in the first round, slumped to 73 on Friday and is tied for 11th at 3 under.
Rickie Fowler, who also opened with 66, tumbled to a tie for 45th at 1 over after a 77. He had one birdie, five bogeys and one double bogey in the round.
--Field Level Media