LEADERBOARD-5 Morikawa, Dahmen; -4 Buckley, Rahm, McIlroy, Hossler, Wise; -3 Hardy, Scheffler, NeSmith, Rodgers, Harman. SELECTED OTHERS-2 Burns, Fitzpatrick; -1 Schauffele, Zalatoris; +1 Thomas, D. Johnson, Rose; +2 DeChambeau, Spieth.
Rory McIlroy and Collin Morikawa are among the biggest names in the hunt at a finely-poised US Open.
World No.1 Scottie Scheffler is also firmly in the frame as he looks to claim his second major title, as is defending champion Jon Rahm.
Overnight leader Adam Hadwin fell away on another tough day at the Country Club, while Joel Dahmen capitalised to come to the fore, joining Morikawa in a share of the lead.
No less than 23 players are within four shots of the lead at the halfway stage, making for a gripping championship at Brookline.
McIlroy had the worst start he could have envisioned when he took three stabs to escape from the fescue on the third, getting up and down for a double-bogey six.
It was, altogether, a mixed round. Birdies were interspersed with bogeys but he came alive on the back nine, clawing back the deficit caused by the disaster on three, then going even better.
“I think I have to go out with the mindset this week that I'm going to try to win my first [major] again,” he said.
“I'm playing as good golf as I've played in a long time. I have a lot of experience.
“Yes, I've won major championships and other big events, but just because I've done that, it doesn't mean that I'll hit better golf shots or I'll hit better putts.
“I'm in a good place. I'm really happy with where my game is at, and I think that's the most important thing.”
At the start of this week, Morikawa had revealed he was unhappy with his swing, having lost his trademark baby cut with little clue how to retrieve it. But the 25-year-old clearly holds himself to extremely high standards – he put on a superb display to reach five-under.
Rahm made big moves, getting to four-under, while Masters champion Scheffler is a shot further back.