Brooks Koepka, Paul Casey, Tommy Fleetwood and Brian Harman share the 36-hole lead at the U.S. Open with all four seeking their first major title.
The quartet are seven under at Erin Hills after a Friday that saw Japan's Hideki Matsuyama surge up a congested leaderboard with a stunning seven-under 65, while the world's top-ranked players were unable to stage recoveries.
Koepka raced out to nine under early in his second round, but dropped two shots on his back nine on his way to a 70.
Despite having a huge power advantage over most of the field, and displaying excellent form with his irons, Koepka was unable to capitalise on a few good birdie chances.
Casey almost watched his U.S. Open hopes sink with a triple-bogey eight on the par-five 14th hole, and a bogey on the next that dropped him to two under for the tournament.
But the Englishman recovered magnificently with five straight birdies from the 17th, and a 71 left him sharing the lead.
Fleetwood (70) joined the group at seven under with a birdie on the par-five 18th, while Harman quietly shot a 70 to make a major cut for just the third time.
Overnight leader Rickie Fowler had people watching on the edge of their seats on Friday, but appeared to play far too conservatively.
After bogeying three straight holes on his back nine, his first dropped shots of the tournament, Fowler limped into the clubhouse with a 73 to fall to six under for the tournament.
Jamie Lovemark made a bomb for birdie on the 18th hole to shoot his second consecutive 69 and be tied for fifth, alongside Fowler and J.B. Holmes (69).
Matsuyama tied a second-round U.S. Open record in relation to par with his seven-under score, and his bogey-free 65 could have been even better. The Japanese star birdied six of his first eight holes Friday, finishing round two at five under for the tournament.
Brandt Snedeker, Players Championship winner Kim Si-woo, Xander Schauffele and amateur Cameron Champ are also two shots back at five under.
Chez Reavie matched Matsuyama's 65 in round two to lead a group at four under. Reavie birdied five of his first seven holes, and eight in all Friday, to surge back into contention.
Reigning Masters champion Sergio Garcia headlines a group still in the hunt at three under.
But the world's top three missed the cut - the first time that has happened at a major since the rankings began in 1986.
Defending champion Dustin Johnson (+4), Rory McIlroy (+5) and Jason Day (+10) will all miss the weekend after their struggles.