But the double bogey he ran up at the 16th hole, on his way to a bitterly disappointing 74, could prove a lot more damaging than the pair of doubles he carded in the opening round of his Masters victory.
McIlroy managed to salvage a level par 72 at Augusta – and followed up with a pair of 66s that propelled him to the victory that finally completed a career Grand Slam
This time, he finds himself at three over par, with a much bigger mountain to climb if he is to win back-to-back Majors for the second time in his career.
And he has to make up a five-shot deficit on co-favourite Scottie Scheffler, after the world No.1 ground out a gutsy two-over-par 69, even though he was also well below his best.
That gap will worry McIlroy more than the eight shots separating him from early pace-setter Ryan Gerrad, after the American journeyman opened with a five-under-par 66.
The World No.2’s big problem was blatantly obvious – his driving, a part of his game that is usually his most potent weapon.
McIlroy’s power and accuracy have been key components in his four previous victories at Quail Hollow, allowing him to overpower a course that has always seemed a perfect fit for his game.
But he hit just three out of 14 fairways, and the wild hook onto the thick stuff on 16 was one of the worst tee shots he has hit in years.
McIlroy started his round on the tenth, so he had plenty of time to bounce back from that double bogey, which is exactly what playing partners Scheffler and Xander Schauffele did, even though they BOTH doubled 16 as well!
Their approach shots ended in the water guarding the green, even though they were hitting from the middle of the fairway.
Both complained that it was due to “mud balls”, after the USPGA controversially decided not to allow players to lift, clean and place on a course that had been pummelled by rainstorms during the practice days.
Scheffler was clearly furious at that decision, saying: ”It’s frustrating to hit the ball in the middle of the fairway and get mud on it and have no idea where it’s going to go.
“I understand it’s part of the game, but there’s nothing worse for a player.
“You spend your whole life trying to learn how to control a golf ball.
“And due to a rules decision, all of a sudden, you have absolutely no control over where that golf ball goes.
“But I don’t make the rules. I just have to deal with the consequences.”
But Scheffler never seems to get too flustered.
Two birdies in the last two holes rounded off that 69, while Schauffle played the back nine in one under to sign for a 72.
It seemed incredible that the best three players on the planet could all double-bogey the same hole.
And it was almost as amazing to see European Ryder Cup captain Luke Donald go bogey-free at a Major for the first time in ten years!
Donald, 47, only plays a limited schedule these days.
But his four under par 67 equalled his lowest ever opening round at a Major, at the 2004 USPGA – and he only hit half of the 14 fairways.
Perhaps he can tell McIlroy how it’s done….
