There was a record-equalling 63 in the Players Championship for a second day in succession as Colt Knost emulated the efforts of Jason Day at TPC Sawgrass.
Twenty-four hours on from Day's spectacular opening round on the Stadium Course, Knost surged up the leaderboard with a nine-under score of his own.
The American, who began the tournament with a level-par round, could even have posted a first 62 in the event, but three-putted for bogey on the 18th after leaving his opening putt five feet short.
"I was nervous on the tee shot [on 18] because I hit it in the water yesterday and took double," Knost said on Golf Channel after his second round. "I was nervous over the four- or five-footer, too.
"When the wind lies down and the course is playing so fast, you've got short irons in. You can be aggressive."
As the morning starters faced friendly conditions once again, four-time major champion Rory McIlroy also threatened to make history with a record low score.
He approached the ninth, his final hole, at nine under, but then took four shots from 89 yards after laying up at the par five.
McIlroy therefore had to settle for a 64, but was nevertheless in contention - two behind leaders Alex Cejka and Jonas Blixt with first-round leader Day yet to tee off.