Johnson was hitting it so well that he appeared to be safe even when he was on the cut line.
That increased the likelihood of a seventh successive major producing a first-time victor, although the likes of Masters champion Sergio Garcia and Martin Kaymer - who claimed U.S. Open glory in 2014 - were handily placed four off the pace.
Jordan Spieth couldn't get anything going on the greens and finished with a 73. He missed the 15-footer. The next one went long, he chipped up to 12 feet and took two putts from there.
World number nine Rickie Fowler has relinquished the lead during through the second round of the US Open. Fowler started on No. 1 made the turn at 2 under after a pair of birdies. New ground, in more ways than one, is being broken in this first staging of a US Open in the state of Wisconsin. No other information was provided. Halfway through the 117th U.S. Open Championship, it's looking like that streak could hit seven.
Willett shot a 9-over 81 in the first round and then withdrew before his tee time in the second round. He's earned four PGA Tour victories and two PGA European Tour titles overall.
Fleetwood, six years Casey's junior, continues to impress in only his second U.S. Open tournament.
"I just didn't putt very well", Johnson said.
"I'm definitely disappointed I'm not playing the weekend, but there is a lot I can take out of it. I think the more rounds I can play, I'm hopefully going to get rid of all that stuff and hopefully strip it down to what you saw the last six holes".
English says "They want par to be a good score, and this afternoon it will be". When it was clear he had nothing going in the second round, he was simply trying to stay out of the way. He has birdied three of his last four holes. He grabbed his putter and pointed it out to his left just as the ball dropped into the cup. The Englishman shot a one-under 71 but had to fight back from two bogeys and a triple bogey in his first six holes.
"You don't often see that in a U.S. Open", Hadwin said. This one he'd rather forget.
He added another birdie on the par-3 13th.
Fowler wasted no time in exploiting the conditions after teeing off on the 10th, rattling off four quick birdies to be four under.
It was day of sizzling drama on the links-style layout that featured stunning birdie runs and spectacular collapses - some like Casey coming on the same scorecard. He tapped in for par.
Paul Casey has a share of the lead heading into the third round. One example of that was Fowler hitting 3-wood into the green on the 632-yard 18th hole, with a breeze at his back. He stumbled to a 6-over 42 over his final nine on Day 1.
"Tomorrow will be a very cool experience", Fleetwood said. His total of 154 equaled his worse two-round total at a major, matching his first two rounds at The Open in 2013.
The performance of the 23-year-old from San Diego has been no less remarkable.
Meanwhile, Graeme McDowell is also in the midst of his second round and is now one shot clear of Dunne on 3-over but also sitting outside the cut mark.
Matsuyama spearheads an Asian challenge which also includes South Korea's Kim Si-Woo, who is also at five under. After another week, it's the WGC-Bridgestone and PGA Championship. But that wasn't the problem.
"Guess what? We get to go home today because Daddy played poorly", Day said to his son, Dash, before walking over to sign autographs. He made an 8, and followed that with a tee shot into the rough to make a bogey.
But the top-ranked players, with the exception of Garcia, who shot 2 under 70, faltered during the opening round.
Other notable players failing to make the cut included British Open champion Henrik Stenson (147), former Masters winners Charl Schwartzel (147) of South Africa and Australian Adam Scott (147) and double Masters victor Bubba Watson (148). He shot 75 and missed the cut.
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