After two days of record scoring, the Los Angeles Country Club North Course -- hosting the championship for the first time -- was proving plenty capable of providing a classic US Open test of patience and nerve.
Clark, chasing a first major title, started the day one off Fowler's lead and birdied the first and third, making the turn at 11-under.
Fowler, who missed the last two US Opens as he battled through a prolonged slump, had two birdies and two bogeys to remain 10-under at the turn, tied with English, who was 10-under through 10.
Rory McIlroy, chasing a fifth major title but his first since 2014, started the day two adrift and was still two off the lead at nine-under through 10 after two birdies and a bogey.
Xander Schauffele, who matched Fowler's record-setting 62 on Thursday, had three bogeys in the first five holes but had clawed back to even for the day with birdies at the sixth, eighth and ninth.
With the course firming up in the hot Southern California sunshine, things were only likely to get more difficult for the leaders.
South Korean Tom Kim fired seven birdies in the first 10 holes to reach six-under for the tournament.
His front-nine 29 tied the US Open nine-hole scoring mark, but he had three bogeys coming in on the way to a four-under par 66 that put him at three-under 207 for the tournament.
He was joined in the clubhouse at three-under by former US Open champion Bryson DeChambeau, who carded a 68.
"To be honest, that back nine is really hard," Kim said. "You just don't really have any bail-outs.
"Those three bogeys really don't feel like bogeys because I barely missed it by a yard or two. But major championship golf, US Open really brings it out of you."
One of Kim's bogeys came at the par-three 15th, playing at just 81 yards on Saturday.
He said the short yardage made it one of the few "realistic" birdie opportunities -- but there was no room for error.
"I mean, it was 76 yards, 80 something to the hole. You have four yards of green to work with," Kim said. "You're long, you're dead; you're short, you're dead."
Masters champion Jon Rahm, who made the cut on the number at two-over, didn't make any headway with an even par 72.
"Today was a US Open," said Rahm, who lifted the US Open title down the coast at Torrey Pines in 2021. "Today is a difficult course.
"Even in the morning it was a little firmer, faster, harder and the margins were much smaller today," added the Spaniard, who was forced to hit away from the pin from the back greenside bunker, then chip back toward the hole on the way to a par at the par-four sixth.
"I played very good golf, I had a great day and on the second nine holes, playing well, I gave myself only two or three birdie options."
The difficulties were evident for former major winners Dustin Johnson and Scottie Scheffler.
Johnson started the day four off the lead and had three bogeys and two birdies on the front nine while Scheffler was one-over for the day through 13.
