The 34-year-old Queenslander is in a tie for 11th at TPC Summerlin, trailing American Tom Hoge who took advantage of pristine conditions on Thursday morning.

Day, who has 12 PGA Tour wins to his name, enjoyed a blemish-free first 18 holes. He birdied the 6th, 9th and 16th, and eagled the par-5 13th.

“It was good. I missed a couple of opportunities for birdie, like easier opportunities for birdie. But overall I'm pretty happy with five-under,” Day said. “Played the par-5s nice today. Didn't get myself out of too much position-wise. There was only one hole where I had a mis-hit of a shot with a chip shot.

“Overall, it's nice momentum going into tomorrow.”

Fellow Australians Lucas Herbert, Harrison Endycott and Cam Davis are one shot back after shooting 67s while Ryan Ruffels brings home the field after a six-over 77.

Hoge did better than he expected in Nevada, making two eagles and no bogeys on his way to an eight-under 63 for a one-shot lead.

South Korea's Si Woo Kim was tied for second with Maverick McNealy of the US after their 64s, while defending champion Sungjae Im joined compatriot Tom Kim in a seven-man group at six-under.

Patrick Cantlay, who has a win and two runner-up finishes in his four appearances at the TPC Summerlin, signed for a 67.

The low round for Hoge was unexpected because he had been fishing off the coast of Mexico the last two weeks, wanting to put the golf clubs away after a long season. He was in the mix for a Presidents Cup pick, though the oversight was not a surprise because he hadn't played well enough since his inaugural PGA Tour victory at Pebble Beach in early February.

"I didn't know where things would stand coming out today," Hoge said.

He holed a 25-foot birdie putt on No.6, then hit a wedge from 110 yards on No.7 that hit the middle of the pin and crashed into the left side of the cup for eagle.

He followed with three more birdies over the next four holes, and then picked up a bonus with an eagle putt on the 16th.

"It was an interesting day," Hoge said.

"I feel like I missed some very makeable birdie putts, but I holed some real nice, long ones for eagle on 16 and some other long ones. Certainly happy with the score, but I've got to make a lot of birdies the next few days."