Justin Rose believes he will need to find an extra gear over the weekend to claim a second US Open title, despite setting the clubhouse target on day two at Pebble Beach.
Rose added a second round of 70 to his opening 65 to post consecutive sub-par scores in the tournament for the first time in his career and the 2013 champion finished two shots ahead of American Aaron Wise on seven under.
Defending champion Brooks Koepka, who is seeking a hat-trick of US Open titles and a fifth major victory in his last nine starts, was ominously placed on four under after a second consecutive 69, with former major champions Henrik Stenson and Adam Scott a shot further back.
Masters champion Tiger Woods is seven shots off the pace after dropping shots at his last two holes in a disappointing 72.
"I'm happy although I felt like it was an opportunity to go a couple better," said Rose, who started from the 10th and went out in 34 after birdies on 15 and 18.
"I felt like I left two or three out there coming in but parring eight and nine at least makes me feel like I've got something out of the day.
"I have no expectations for the weekend really. I just like my position, the course and the way I'm trending but I still don't feel like I'm cooking and I'm going to need to find that (extra) gear if I'm going to hoist some silverware on the weekend."
Rose had birdied his final three holes on Thursday to card a 65 which equalled the lowest round in a US Open at Pebble Beach set by playing partner Woods on his way to a record 15-shot win in 2000.
The 38-year-old had the chance to extend his lead as one of the early starters and followed five straight pars with a birdie from six feet on the 15th before getting up and down from a greenside bunker on the 18th for the second day running.
Rose was annoyed to bogey the first after missing the fairway despite taking an iron off the tee, but bounced back to birdie the second before another errant tee shot on the fourth cost him a second dropped shot of the day.
Koepka could also reflect on a number of missed opportunities but remained well placed to maintain his remarkable recent record in majors and join Scotland's Willie Anderson (1903-05) as the only player to win three straight US Opens.
"The funny thing was I was hitting good putts, they just weren't going in, but my ball-striking was tremendously better today. I was very pleased with it," the world number one said. "I never really felt like I had to work, it was quite an easy round.
"I'm good at this patient game, I know you just need to be hanging around on the weekend. I would have liked to have been leading but I'll take it. I have a chance, just have to clean it up for the weekend. If I can putt the way I did on Thursday and hit it like I did today it's a good combination."
Open champion Francesco Molinari was within two shots of the lead when he chipped in for the second time in the space of four holes on the seventh, only to double bogey the eighth and drop another shot on the ninth and finish two under.
"A shame about the finish, but it's only halfway," the Italian said. "So I need to hit the ball and be better than today if I want to contend at the weekend."
Woods, who single-putted 11 greens in an opening round of 70, was on course for his first bogey-free round in any US Open since his final round here in 2000 after one birdie and 15 pars, but bogeyed his last two holes.
