That traumatic experience was only 68 days ago but the Ryder Cup star showed yesterday he is not haunted by it. "I don't know if it says that I've just got a very short memory," he joked after out-scoring playing partner Phil Mickelson by nine.
"I learned a lot from it, but going into the US Open you can't be thinking about what's happened before. You've got to just be thinking about this week and how best to prepare and how to get yourself around the course.
"You definitely have to analyse the parts that you want to do better but I really stopped thinking about the Masters a week after."
This is the third time in four Majors McIlroy has held the lead after the opening day. He shot a 65 at Augusta and a Major record-equalling 63 in last summer's Open at St Andrew's where he was promptly blown away by howling gales for an 80.
With only Masters winner Charl Schwartzel, of South Africa, and Korea's YE Yang within sight of him on three under, McIlroy has no intention of offering further evidence that he could become an habitual choker.
Ahead of starting his second round early this afternoon, he said: "The first three days at Augusta I played aggressively. I played smartly but I played aggressively to my targets and aggressively to the spots I wanted to hit it.
"But, going into the Sunday, I started to play defensively and that's when things can go wrong. This week it's about being aggressive to the spots. On a lot of holes I'm just trying to hit it to the 150-yard plates off the tee, and then playing my iron shot in from there."
Playing aggressive, or going defensive on a course that is penalising any error, was the dilemma facing the two Britons ranked first and second in the world, Luke Donald and Lee Westwood, who were in danger of missing the cut.
Westwood was tied with Ian Poulter for 84th place after returning a 75 which he described as "c**p". Donald shot one better and was tied for 62nd out of a field of 156 players. He said: "This course is going to get more difficult and hopefully that will play into my hands as long as I start controlling the ball a little better."
Defending champion Graeme McDowell, of Northern Ireland, was one under. "No complaints," he said. "I parred the place to death on the back nine but I'm happy with that."
