Tyrrell Hatton fired four birdies and an eagle in his first nine holes and finished with a seven-under-par 65 to take a one-stroke lead, while Shane Lowry and Rory McIlroy struggled to keep pace in the first round of the PGA Tour's CJ Cup in Las Vegas.
Starting on the back nine, Hatton seized the momentum early in his round at the Shadow Creek course when he holed out from the fairway for an eagle on the par-four 12th.
Hatton, who won the European Tour's BMW PGA Championship in Surrey on Sunday and turned 29 on Wednesday, is a shot clear of Americans Russell Henley and Xander Schauffele as he guns for his second PGA Tour victory.
Lowry is on level par after a mixed round. The Irishman battled and fought throughout and was two-under at the turn but a double bogey at his final hole undid much of his good work.
It was a similar story for McIlroy who was one under at the turn but struggled to close out his round and finished with three consecutive bogeys to leave him on +1
Hatton had no such problems, despite feeling the effects of travel. "It's fair to say I'm pretty tired at the moment," he said.
"Still struggling a little bit with jetlag. And you can tell by my voice, picked up a little bit of a sore throat if you like on the way over.
"Today was a long day. Very happy with my score and I just need to try and get back to the hotel this evening, have a good rest and hopefully sleep better than I did last night. Fingers crossed for another good day tomorrow."
Dustin Johnson withdrew from the no-cut, 78-player event after a positive COVID-19 test but even without the world number one the tournament has a very strong field.
World number two Jon Rahm is tied for fourth after carding a five-under par 67, while defending champion and world number three Justin Thomas had an even par 72.
The CJ Cup was switched to Las Vegas from South Korea this year because of travel restrictions imposed due to the pandemic.