Rory McIlroy made no attempt to hide his frustration after squandering a two-shot lead with eight holes to play as China's Li Haotong claimed the biggest win of his career in the Omega Dubai Desert Classic.
McIlroy overturned a one-shot overnight deficit with the aid of three birdies in the first 10 holes at Emirates Golf Club, but bogeyed the 11th and 16th as well as three-putting the par-five 13th for par.
And although the four-time major winner birdied the final two holes, Li did likewise under enormous pressure to complete a closing 69 and win by a single shot.
Li's 23-under-par total is a tournament record and gives the 22-year-old a second European Tour title, as well making him the first male Chinese player to break into the world's top 50.
Li will also make his Masters debut in April and can become the third straight Dubai champion, after Danny Willett and Sergio Garcia, to claim a green jacket. McIlroy needs to win at Augusta National to complete a career grand slam.
McIlroy has now finished third and second in his two starts since calling an early end to an injury-plagued and winless 2017 campaign, but will be disappointed at failing to convert a two-shot lead at halfway.
Asked his reaction at missing out on a first win since September 2016, McIlroy told European Tour Radio: "Yeah, p***** off.
"It was a couple of bad shots, a couple of poor decisions, a couple of mental errors, a few tentative putts out there, as well. I kept leaving myself in places where I couldn't really give it a run at the hole because they were downhill, downgrain, downwind.
"But I tried until the very end. Made two good birdies. Made him win it in the end, which was all I could do, and he played very well on the way in, birdieing three of the last four. I just wish I could get a couple of those holes back.
"If someone had told me at the start of the year you'd finish third and second your first two events, I'd say, yeah, I'd take that. But being in the positions I've been in and having two close calls it's a little difficult. The competitor in me is very disappointed right now. I wanted to win. I always want to win, and I just didn't do enough when I needed to."
Li, who birdied four of the last six holes, said: "It's incredible, I'm so happy. Over the last four holes I hit some of the best shots of my life.
"I just didn't realise I could make that putt on 15. That was huge. I think that was the turning point. And especially on 18, didn't realise I would make that one, either.
I believe I think my game is in good position now, and especially after this week, it gives me a lot of confidence back, especially last week, missed the cut. So never been in this position again. Just want to be myself and play some decent golf in the future."