McIlroy felt he was still in contention despite starting six shots off the lead held by 21-year-old American Matthew Wolff, yet immediately made his task almost impossible.
The four-time major winner found the fairway and green in regulation on the opening hole, but four-putted from 90 feet after his first attempt failed to get over a ridge in the putting surface and rolled back towards him.
McIlroy also bogeyed the fourth and seventh, and although he stopped the rot with a birdie on the ninth, the easiest hole on the course all week, his chances had realistically gone.
At four over par, McIlroy was eight shots behind Bryson DeChambeau, who had covered the first six holes in one under to overhaul Wolff at the top of the leaderboard.
Aiming to become the first player since 1913 to win on their US Open debut, Wolff dropped shots on the third and fifth to fall a shot behind his playing partner.
If McIlroy had felt hard done by on the first, then Harris English would have been absolutely livid after losing a ball in the rough to the left of the first fairway.
Happening right now with Harris English... #USOpen https://t.co/4xvw73jW4H
— U.S. Open (USGA) (@usopengolf) September 20, 2020
Club members had been employed as spotters throughout the week, but despite their efforts and those of English and playing partner Xander Schauffele, the ball could not be found within the three-minute time limit.
That meant a trip back to the tee and English eventually did well to get up and down from a greenside bunker to match McIlroy’s six, before regaining his composure remarkably quickly and holing a bunker shot for a birdie on the next.
