At the top of the leaderboard, Collin Morikawa matched the low score of the championship with a 4-under 66 for a share of the 36-hole lead with Joel Dahmen and a shot at a third straight year winning a major.
He had plenty of company at The Country Club, one player in clear view.
Defending champion Jon Rahm played with Morikawa and did his best to keep pace with an eagle and a series of big par putts that felt just as valuable. Rahm had a 67 and was one shot behind in a group that included Rory McIlroy.
McIlroy, coming of a win at the Canadian Open, was never more entertaining.
He was two holes into his round when an errant approach landed in waist-high fescue. He took a hack. And then another. The third try finally found the green, and he holed a 25-foot putt to salvage a double bogey. McIlroy hit his stride on the back nine with three birdies over his last four holes for a 69.
Not to be overlooked was Masters champion Scottie Scheffler, who chipped in from thick rough short of the par-5 14th green for an eagle that brought the Texan back into the mix with a 67. He was two shots behind.
"It's the US Open. No one has taken it deep so far and kind of run away," Morikawa said. "The last few days is a huge confidence booster for me heading into this weekend, and hopefully we can kind of make some separation somehow."
Morikawa, Rahm and Scheffler have combined to win four of the last nine majors. And then there's McIlroy, who has four majors by himself, but none since 2014.
"I think it's great for the game of golf that the highest ranked players and the best players are up there, especially in the tournament where truly the best player ends up winning," Rahm said.
The idea of the US Open is to identify the best players. Some of them require some introductions to major championship contention on the weekend.
Start with Dahmen, the cancer survivor and everyman who will never be accused of taking himself too seriously, even if he takes his game seriously. He thought about withdrawing from the 36-hole qualifier twice last week, before it started and after the first round.
But he stuck it out, and with a 68 on Friday, plays in the final group of a major for the first time. He joined Morikawa at 5-under 135.
The group one shot behind includes Hayden Buckley, who actually studied while at Missouri because he never thought playing golf for a living was going to work out. He wasn't in the US Open until making a 20-foot birdie putt in a playoff for the last spot in his qualifier 11 days ago.
He was fading, like so many others, with three bogeys during a five-hole stretch around the turn when he got back on track. Birdies on the last two holes gave him another 68.
Also at 136 were Aaron Wise, with one PGA Tour victory and nothing better than a tie for 17th in his nine previous majors; and Beau Hossler, who featured on the weekend at Olympic Club as a teenage amateur in 2012 but hasn't been heard of since then in the majors.
They were examples that the US Open being open to all doesn't just stop with qualifying for the right to play the toughest test in golf.
Ko moves inside top 20 in Michigan
Meanwhile on the LPGA Tour, Lydia Ko had more success than her male counterparts, firing a four-under second round to give her a chance at a decent finish in the Meijer Classic.
Ko recorded five birdies and a bogey amidst windy conditions at the Blythefield Country Club. However, despite the solid round and the fact she's sitting in a tie for 17th on the leaderboard, her hopes of contending for the title are slim; given she's a full eight shots behind clubhouse leader Jennifer Kupcho.
Kupcho opened a two-stroke lead over defending champion Nelly Korda after shooting a 5-under 67 to follow up a career-best 63 on Friday.
Korda holed out from 82 yards for eagle on the par-5 14th in a bogey-free 65. She's making her second start since returning from a four-month break because of a blood clot in her left arm.
- with AP
