McIlroy came from four down to win the first round of the WGC-Accenture Match Play Championship, but Padraig Harrington and Graeme McDowell were among those beaten.
McIlroy pulled off a brilliant victory from the jaws of defeat after he lost four of the first six holes to American Kevin Na early on and was still two behind with only four left.
But the 20-year-old fourth seed eagled the next and won on the final green as Na, ranked 61st in the world, crumbled.
It was just the sort of thing that would have hugely impressed Ryder Cup captain Colin Montgomerie, who earlier this week said: "I want to see guys who show guts and determination, guys who are maybe two or three down with four or five holes to play but who battle back to win."
The young Northern Irishman, already a near-certainty for a debut against the Americans in October, reached the quarter-finals last year and is this week playing his first event as a member of the US Tour.
McIlroy is already the only Irishman left in the event as it moves down to the last 32, Graeme McDowell having gone down 2&1 to in-form Luke Donald.
McIlroy said: "I definitely didn't make it easy for myself. I got off to a very slow start.
"I think I hung in well, but was pretty fortunate to get through and I'll need to play better if I want to progress into the latter stages."
He next faces Oliver Wilson, who had a fine win over Dubai Desert Classic winner Miguel Angel Jimenez, and added: "Ollie's a great competitor, a Ryder Cup player and he's going to be very tough."
McDowell commented: "The last two years I've run into a buzz-saw.
"Last year Zach Johnson made eight or nine birdies and Luke just putted the eyes out of it. Every time I smelt a chance he made a putt.
"It does not matter how well you play in this. If someone plays better you go home."
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