World number nine Rickie Fowler has relinquished the lead during through the second round of the US Open.
The 28-year-old started day two with a one-shot cushion but a one-over-par 73 opened the door for a four-way tie for the lead at seven-under shared Paul Casey, Brian Harman, Tommy Fleetwood and Brooks Koepka.
As day two action draws to a close, Fowler has fallen to a share of fifth at six under, alongside compatriots Jamie Lovemark and JB Holmes both on 69.
Earlier, Australian Marc Leishman maintained his solid position on the leaderboard, shooting a gutsy even-par round of 72.
Leishman is currently sharing 13th place, three shots off the pace.
"It was definitely a lot more like a US Open today than yesterday the greens were a little quicker again," Leishman said.
England's Casey had an action-packed second round. He birdied five-straight holes, starting with the 17th after teeing off on the 10th, but that run only served to negate a triple bogey on 14 as well as bogeys on 12 and 15 to card a one-under 71.
The projected cut-line for the top 60 players and ties is one-over, starting the day in a respectable position of even-par, Adam Scott sealed a likely early exit with a disappointing 75.
Jason Day's struggles continued. He picked up one shot on his first nine, after an opening-round 79, but a double bogey on the fifth and a second-round 75 sunk him to finish 10-over for the tournament.
Jordan Spieth sits just inside the cut-line at even-par through 16 holes, while playing partner and defending US Open champion Dustin Johnson is flirting with a missed cut at three-over.
Rory McIlroy's 71 wasn't enough and he'll miss the cut at five-over.