Shane Lowry's hopes of becoming European number one look to be over after he slumped to a one over par round of 73 at the DP World Tour Championship.
Lowry started off with two birdies, but three bogeys over his closing 10 holes took the gloss off the Open champion's round.
For McIlroy, it was sensational golf. The Ulsterman carded seven birdies and eagled the last hole for a 64.
McIlroy trails leader Mike Lorenzo Vera of France by one shot.
In-running, Lowry is now fifth in the Race to Dubai.
Austrian Bernd Wiesberger is still out in front to top the charts at the end of the week following a 2 under par round of 70.
However, Wiesberger will have competition towards the weekend.
Irish Open winner Jon Rahm carded a six under par round of 66, while Tommy Fleetwood, who won in South Africa last week, fired a 67.
It leaves Rahm second in the in-running standings, with Fleetwood third.
That the course played in such a benign fashion meant it was the perfect platform for McIlroy to continue the form that has seen him win four times worldwide in 2019. He loves the Jumeirah track in the Middle East and is primed for another big finish over the next three days.
Shane Lowry didn't want talk to bounce around this week that he was settling for his claret jug ahead of the season finale, so he'll be disappointed with his start. Hopefully he can shoot some scores in the 60's over the next few days.