Then just as quickly, it looked like he was heading for another Augusta National meltdown.
In the end it was neither. The Northern Irishman shot a first round of even-par 72. No harm was done but no great inroads were made either.
"It could have been better," McIlroy conceded. "I felt like I played well and gave myself plenty of opportunities."
McIlroy birdied three of his first nine holes to reach the turn at two-under-par and seemingly ready to make further gains on the back nine.
But no sooner had he started his run, then he began to fall back and memories of his collapses in the previous two years came back.
He bogeyed the 10th hole, then the 12th, the 14th and finally the 17th. He recovered two of the shots with birdies but signed for a 72.
"I just made some silly mistakes, a couple of three-putts on the back nine," he said.
"I made enough birdies but I just need to cut those mistakes out and I'll be fine."
While McIlroy's 72 was seven shots worse than his first round score in 2012, the 23-year-old was relieved to escape without any major problems.
Two years ago, he led the Masters by four shots at the start of the final round before suffering a meltdown, shooting an 80 to plunge down the leaderboard and finish tied for 15th.
Last year, he was tied for third at the halfway stage but crashed out of contention with a third round 77. He contained the damage on Thursday.
"I turned in two-under par and everything felt good. That was the story of the day any time I got a bit of momentum I gave it straight back," he said.
"Around this course you really can't do that. I feel like the game is there, I mean I hit the ball really well."
Although still not at his best, there were plenty of positives for McIlroy, who has struggled with his game this year.
He has not won a tournament in 2013 and lost his number one ranking to Tiger Woods. At last month's Honda Classic in Florida, he quit during the second round, prompting speculation he was having problems adapting to his new Nike clubs.
McIlroy insisted his equipment was not the problem, blaming his exit on a sore tooth.
But he hit the ball cleanly from tee to green on Thursday only to be let down by his putter needing 32 putts to complete his round. Only 13 of the 93 starters took more.
"As long as I keep giving myself birdie opportunities like that and take a few of them, hopefully I can go out and post a good one tomorrow," he said.
"I am getting there. I think I am hitting the ball just as well. It is just a matter of taking the opportunities and limiting the mistakes."
- Sports & Recreation