Venezuelan rookie Jhonattan Vegas and American William McGirt shared the first-round lead at the US PGA Tour's Las Vegas stop on eight-under par 63.
Vegas, who won the Bob Hope Classic in January for his first US Tour title, had 10 birdies and two bogeys on the TPC Summerlin layout as the American circuit's Fall Series of events kicked off.
McGirt, another PGA Tour rookie, had eight birdies without a bogey.
Vegas, who played in the heat of the afternoon, got to eight-under with back-to-back birdies at 15 and 16, but gave back a stroke with a bogey at the par-three 17th before a birdie at the last.
"I feel like I'm hitting the ball absolutely great, which is something fun to do," Vegas said. "But the main thing was I made a lot of putts today.
"The two greens I missed today, I missed by probably half an inch. And just putting from the fringe I three-putted both times, which was kind of ironic. It's just golf. You have to stay positive, and the more positive you can be the better you'll be out there."
McGirt, who played in one of the last groups of the day, had five of his birdies on the back nine to claim his share of the lead.
Green had set the early pace with a round that featured seven birdies and no bogeys.
The Australian, who missed the PGA Tour's FedEx Cup playoffs, was making his first start in more than a month. In his last outing, he finished equal 52nd in the Wyndham Championship.
The time off appeared to do him good, as Green hit 10 of 14 fairways and hit 14 greens in regulation.
"Today it just sort of all clicked a little bit," said Green, whose 64 matched his lowest total of the year.
"I made a couple of really nice up-and-downs, but it was just one of those real steady rounds where I just managed to pick up ... probably three or four sort of unexpected birdies out there," Green said. "No bogeys, which was pretty unusual."
Green, winner of the 2009 Canadian Open, came into the week ranked 178th on the money list, but said his focus is on playing well more than on securing his card for next season.
"I would like to keep my card, but even if I didn?t, just to play some nice golf, just would take the pressure off," said Green, whose last top 10 finish was at the Sony Open in Hawaii in January of 2010.
Although Green had set an early target, McGirt said he wasn't really aiming at it.
"I was just trying to make as many birdies as I could," he said. "I knew there was a seven-under posted before I even teed off. So you knew it was out there, and it was just a matter of staying aggressive and making some putts."
Source: AFP Global Edition