England's Paul Casey shot an eight-under-par 62 as he made a superb start at the Sony Open in Hawaii.
The 37-year-old carded nine birdies at the Waialae Country Club in Honolulu and he shares the lead after day one with American Webb Simpson.
The only blemish on the three-time European Ryder Cup player's card was a bogey five on the sixth hole, which was his 15th.
Simpson also played the back nine first, but was only one under at the turn.
He hit form with a run of seven birdies in his last nine to join Casey on a score that was just one short of the competitive course record.
Simpson, who ditched his long-favoured belly putter for a short one, was thrilled with his display.
"Today was a big day for me," he told the PGA Tour website. "It was one of my best putting rounds I've ever had to be honest."
Simpson's compatriot Robert Streb and Colombian Camilo Villegas also had strong rounds and they sit one shot behind the joint leaders.
Streb recovered well with an eagle on the par-five ninth hole after two quickfire bogeys, while Villegas flew out of the traps with six birdies on the front nine but could only add one more after the turn.
South African Rory Sabbatini is out on his own on 64, while Australia's Jason Day and American JJ Henry head a six-strong cluster three shots off the pace.
Australian Geoff Ogilvy is way back on one under, but he still had a day to savour in Hawaii as he aced the par-three fourth hole.
At first Ogilvy was not sure what had happened, but he knew straight away he had struck it sweetly.
"It was a quality shot, I figured it was going to be somewhere near the hole," Ogilvy told the PGA Tour website. "But the reaction was pretty... subdued. I wasn't sure if it went in or dribbled off the back."
When asked how many times he had managed a hole in one the 37-year-old estimated around six or seven but said it was only his second at a professional event.
"I think it's around that number," he said. "It's bad that I can't remember, but most of them have been in hit-and-giggle types of games with my buddies."
