Thomas Pieters delivered a composed final round to claim the biggest win of his career with victory in the Abu Dhabi Championship as Shane Lowry's challenge faltered.
Pieters, who turns 30 next week, finished one shot clear of Spaniard Rafa Cabrera Bello and outsider Shubhankar Sharma, to take his sixth DP World Tour triumph and the €1million winner's prize.
Frenchman Victor Dubuisson took a tie for fourth alongside Viktor Hovland, while defending champion Tyrrell Hatton recorded an eagle and four birdies to finish three shots back in sixth place with countrymen Ian Poulter and James Morrison.
Scotland's Scott Jamieson, who held the overnight lead, carded a disappointing five-over 77 to finish four off the lead in 10th.
Lowry was one shot behind Jamieson following Saturday's play, but he too endured a final round to forget which started with a triple-bogey seven on the opening hole. He ended the day with a five-over 77.
"I'm happy I can finally get my caddy, Adam a gold bib [for winning a Rolex Series event]," said Pieters, who finished with a final-round 72.
"I chickened out on the last. I was gong to go for it but I was told I was two ahead so I decided to lay up and I made a [par] five which was fine.
"I just hope all the juniors back in Belgium are watching this. I used to think it was impossible, but when Nico [Colsaerts] came on the scene and started winning that was inspiring and I hope that is the same for the kids back home."
McIlroy will be pondering what might have been after he moved to within two of the lead, courtesy of a superb 141-yard eagle on the par-four ninth and a birdie on 13.
But his round fell apart with three bogeys in the final five holes - the Ulsterman eventually ending the week with a three-under 69 in a tie for 12th.
"Honestly, I am just happy that I got to play an extra two days," said McIlroy.
"I had to make a birdie on the last hole on Friday night just to be here, and I almost made the most of the weekend.
"I played well yesterday, and really well today through 13, and then a couple of loose shots coming in cost me.
"It wasn't the finish I wanted, but big-picture wise it was good to play another 36 holes and assess where everything is and know what to work on."
Padraig Harrington gave himself an outside chance of competing in the final round by posting an impressive 68 on Saturday, however, the three-time major winner had to settle for a level-par 72 and end in a tie for 20th on four under, one shot behind Lowry and McIlroy.
Jamieson led after every round at Yas Links, setting the pace with a brilliant opening 63 and staying ahead with a 74 before heading into the final round with a one-shot advantage over Pieters after a 68.
But the 38-year-old, whose sole World Tour sole triumph came nine years ago over 36 weather-affected holes and a modified layout at the Nelson Mandela Championship, was unable to recover from a poor start, which included four bogeys in the first five holes.