Defending champion Shane Lowry recovered from an early double bogey to open with a two-under-par round of 70 at the Abu Dhabi HSBC Championship.
After giving away two shots on the third hole of his round, the Offaly man went on to have five birdies and one bogey.
It leaves the Open winner trailing leaders Shaun Norris and Renato Paratore by six strokes with world number one Brooks Koepka two shots back at six-under.
Former Masters winner Sergio Garcia is in a group of five players at five-under.
Koepka is playing his first tournament since suffering a knee injury in October and he's happy with his start:
"It feels good to be back, I missed the competition," the American four-time major winner told European Tour Radio.
"Played really solid, drove it really well, controlled the ball flight.
"When you do have a morning tee-time you've got to take advantage of it. I did that today.
"(Knee) Feels fine. It was a little sore last night - that's expected," he admitted. This is the first week I've walked 18 holes, and I've done it three times already. It's a little tired."
Padraig Harrington is four-over-par into day two after dropping five shots on his last five holes.