Justin Thomas has gone from a fast finish one day to a fast start the next, and it has carried him to a seven-under 65 and a one-shot lead in the PGA Tour's Zozo Championship at Sherwood.

Thomas - who required just 29 shots on day one's back nine - was not particularly thrilled with his performance after he closed with six consecutive pars on a day when the field made birdie or better just over 33% of the time.

Richy Werenski led the way with 12 birdies for a 61, the lowest score in a Tour-sanctioned competition at Sherwood. The average score was 67.87.

Tiger Woods managed to beat that, making eight birdies in his round of 66, but still could not pick up any shots against the lead.

The defending champion remains 12 shots behind.

Thomas finished with a 14-under 130, one stroke clear of Lanto Griffin and South Africa's Dylan Frittelli, who each completed their round of 65 with bogey on the final hole.

Patrick Cantlay found his putting touch and and shot 65. He was two shots behind, along with Scottie Scheffler, who also had a 65.

Cameron Smith is the highest-ranking Australian after 36 holes, carding 69 on day two, leaving him in joint-27th place on leaderboard at eight-under.

Former world No.1 Jason Day (71) sits three shots further back on 139, level with Brad Kennedy (67), while Marc Leishman rounded out the Aussie contingent with 73.

Low scores were everywhere on a course that is short by PGA Tour standards and has five par-fives that are reachable in two. There has been little wind and pleasant conditions.

Thomas has won the last four times he has held a 36-hole lead, though this is different, with 20 players within four shots of the lead, all of them at 10-under or better.

"I played well, (although) I'm not very pleased with the finish," he said.

"The last six holes I would have liked to at least have got something. I just wasn't near as tight and tidy those last four holes."