He was the only player under par among those who played Friday morning in a unusual mixture of weather that began with an overcast sky, gave way to two hours of light rain and then returned to mild sunshine.
Below is a look at how things stand at Shinnecock Hills in Southampton, New York, at the midway point.
Johnson was concerned with staying out of trouble, and he has done that well on a punishing course. He shot 82. He has endured more than his share of bad luck, bad breaks and bad shots in the majors.
"It's just what I've done the last few events, I just haven't putted well".
"Dustin is playing great golf - anyone who is going to catch him is going to have to play really, really well."
Well, he is back at it again early on in NY. It's the same obstacle facing Serena Williams who, as she works her way back from having a baby, enters a competitive landscape where other players have had a taste of winning. His shot of the day came on the 7th green, when he nailed a 45 foot putt for birdie.
Johnson has been about the only golfer in the field to have any sort of sustained success on the course.
Jordan Spieth joined them in the most unlikely fashion.More news: Farm Bill Looks to Protect Dairy Farmers in Minnesota
While Johnson has a grasp of the course, the same can't be said for other stars.
Tiger Woods is a combined 5-over on the first hole through two rounds. This is the second straight year he is No. 1 at the U.S. Open, ending a streak of six straight years with a different No. 1 at this major. His first nine holes included four bogeys, two double-bogeys and endless sighs of dismay.
Tiger Woods missed the halfway cut at the US Open, the day before the 10th anniversary of his last major title success in the latest sign his comeback from major back surgery has stalled.
'I'm not very happy with the way I played or putted, ' said Tiger, who finished 14 shots behind his playing partner. "I'm 10 over par". "You never know what's going to happen".
McIlroy's implosion wasn't as dramatic as Spieth's, but he struggled mightily off the tee, repeatedly driving it in the knee-high fescue.
Woods responded with a birdie at the par-five 16th, but he gave the shot back at 18 when another wayward drive hit a marshal and dropped into a bad lie in the rough, from where he gouged his second into a greenside bunker.
The second hole is a rude awakening for most golfers. But the cut line actually wound up being eight-over.
SOUTHAMPTON, N.Y. - There are many distinct ways to tell, as a viewer, you are watching a brutally hard U.S. Open setup. It was just the Englishmen for this walk from tee to grass, the only group who'd committed to trailing Poulter through what had begun to look like the best round of golf of this year. The latter finished with four late birdies but still missed out by two shots - a classic example of a man able to play freely only when his chance had gone.