Colin Morikawa and Joel Dahmen share US Open lead, but Rory McIlroy and Jon Rahm maintain challenge

Open champion Morikawa carded a superb 66 to finish five under, with Dahmen sneaking through the pack to draw level at the end of the second round.

McIlroy and Rahm and joined by Buckley and Wise on four under, with Scottie Scheffler, who won the Masters this year, is also involved at the top of the leaderboard one shot behind.

Matt Fitzpatrick is clinging onto the coattails of the leaders as well as he finished his second round two under.

Northern Irishman McIlroy had been in danger of falling out of contention when he covered the front nine in 36, the world number three needing three attempts to hack on to the green from thick rough on the third, before holing from 23 feet to salvage a double bogey.

But after dropping a shot on the 10th, McIlroy picked up shots on the 12th, 14th and 17th to remain firmly in the hunt for his fifth major title and first since the 2014 US PGA.

Scheffler was two over after seven holes but then birdied the eighth and 13th, holed out from 55 yards for eagle on the par-five 14th and picked up another shot on the 16th in his bid for an amazing fifth win in 2022.

"I just stayed really patient," Scheffler said. "I was hitting it good pretty much most of the day. Two silly bogeys early in the round, but outside of that I hit it really good.

"If a few more putts would have fallen in versus (running) around the edge, it would have been a really special day. But three under was a good score for me, especially being two over through six."

Speaking about his eagle on the 14th, Scheffler added: "I hit a great drive down the middle and then had kind of a funny lie where it was sitting on a downslope and it made that shot into the green much harder.

"I caught it a hair thin and hit the tree. Fortunately it didn't hit the tree and come backwards, it kind of just fell down in front of it. Had a good lie and hit a good chip and it went in."

Fitzpatrick recovered from a hat-trick of bogeys to play his final five holes in two under par as he looks to secure a Brookline double following his US Amateur triumph here in 2013.

"I played really, really well," said Fitzpatrick, who was fifth in the US PGA last month. "Three of my four bogeys were three-putts, so that kind of sums up the day.

"Felt like I hit the ball tee to green really, really good. I think I hit one chip shot all day, so that kind of summarizes how well I felt like I hit it.

"I feel like I've left a couple out there, which to say in a US Open is pretty rare, but it is positive going into the weekend."

Twenty-five players had recorded scores in the 60s in the first round, equalling the second most in tournament history and just two behind the record of 27 at Pebble Beach in 2019.

But with a blustery wind helping to dry out the course, six-time major winner Nick Faldo predicted conditions would continue to get tougher over the weekend.

"It really is nasty, gusty, blustery, and there are some really tough holes," Faldo, who lost a play-off to Curtis Strange in the 1988 US Open at Brookline, said after completing commentary duties for American broadcaster CBS.

"To be honest anybody in red numbers will be very happy and in a great spot. It's only going to get tougher. They can let this course go and it could be really tough."

However, with a thunderstorm which threatened to bring stronger winds skirting The Country Club, the later starters were able to exploit good conditions to climb the leaderboard.

South African qualifier MJ Daffue had reached six under earlier in the day when he holed from 80 feet on the seventh, only to play his last eight holes in five over.

World number eight Viktor Hovland had been just a shot off the lead after two early birdies, but bogeyed six holes in a row around the turn and dropped three more shots on the closing stretch to shoot a dispiriting 77.