Justin Thomas has set a new PGA Tour record at the Sony Open in Hawaii, becoming the youngest ever player to shoot a round of 59.

The in-form 23-year-old hit eight birdies and two eagles en route to the feat as he became only the seventh golfer to break 60 on the tour.

"It was obviously a fun day," he told reporters afterwards. "I just kind of had it rolling out there. All my birdies were easy, it wasn't like I made any long putts or anything.

"But it's not like winning the tournament you know. It's an unbelievable round, but you have three days left still. So I didn't really know how to react."

Elsewhere, Hudson Swafford ended the opening day second on the leaderboard, three shots back at 62, while South Africa's Rory Sabbatini hit a 63 for third.

Jordan Spieth went five-under for tied 12th, with Justin Rose and Webb Simpson both one shot further back.