And the former Ryder Cup player then made it five birdies in succession - just one short of the US Open record equalled by Adam Hadwin on Thursday - by picking up shots on the first, second and third.
He was a long shot to make the cut Friday after opening with a 79, his worst score ever in a U.S. Open, and he removed any suspense when he hit a wedge over the green at No. 2 (his 11th hole) and then started hitting his tee shots in the hay.
With the cut on another low-scoring day coming at one over, Johnson seemed poised to scrape into the weekend after three birdies and a bogey left him at two under, one over outright, midway through his second round.
But any bad taste in his mouth shouldn't last long because it's been an impressive week for the 29-year-old Valspar Championship victor from Abbotsford, B.C. In Thursday's first round, he tied a U.S. Open record by making six consecutive birdies en route to a four-under 68 and a share of seventh place.
After starting on the back nine, defending champion Dustin Johnson struggled to a 75, making only one birdie. This is the first time in major championship history that the top-three ranked players have failed to make the cut.
Brooks Koepka, Brian Harman, Tommy Fleetwood and Paul Casey were all at 7-under par through Friday's second round. "And I've been very light on competitive rounds this year, and it's just a matter of getting into a good round of golf now". His 7-under par tied the record to par for the first round of a U.S. Open held by Jack Nicklaus and Tom Weiskopf, who each shot 7-under 63 at Baltusrol in 1980.
"Myself and Rory, we didn't quite have the greatest tee game yesterday and it showed in the scores", said McIlroy, who finished at five-over.
Most freaky about Thursday was that as many amateurs broke par as top 10 players in the world - two apiece.
" I saw some positives on the back nine to take into next week and, even though this is disappointing, the last two rounds will serve me well in this busy summer".
More twists and surprise to come in Champions Trophy?
He went on to say, "We all know what happens and what not, and I can't tell you how they have won the games, I can't name them". Pakistan then cruised to their victory target, finishing on 215 for two with a massive 77 balls to spare.
Day, who won the 2015 PGA Championship up the road at Whistling Straits, had to birdie his last hole Thursday to break 80.
PGA Tour rookie Xander Schauffele and veteran Brit Paul Casey closed to within one of Fowler, adding drama late in the day. I'm looking forward to it very much.
The 44 subpar rounds broke the first-round mark of 39 at Medinah in 1990.
The leading South Africans are two-time US Open champion Ernie Els and Thomas Aiken, who are tied for 24th at 2-under-par.
"It doesn't need to be too much of a change for this golf course to play pretty hard", he said. The top 18 players on the leaderboard going into the weekend have combined for zero majors. I guess I've just kind of always been that way.
QUOTEWORTHY: "I'm not here on the weekend, so it's unfortunate".
Playing just his seventh tournament of the year due to a rib injury, McIlroy bounced back with a birdie from 12 feet on the 13th, but at six over par he remained five shots outside the projected cut mark.