Jim Herman opened up a two-shot lead at the Valspar Championship with a blistering nine-under 62 in the first round on Thursday.
The American holed nine birdies in Palm Harbor, Florida, to top the leaderboard before darkness led to play being suspended.
Herman started on the back nine and birdied five of his first seven holes in a strong opening to his round.
Another four birdies followed, including three in a row from the third to the fifth, as he took a two-shot lead.
Swede Henrik Stenson and Russell Henley are just behind Herman after starting with 64s.
Like Herman, Stenson went through bogey-free, while Henley's only blemish came on his opening hole - the 10th.
James Hahn (65) is at six under, a shot ahead of Irishman Seamus Power (66).
Bryson DeChambeau is the best-placed player yet to complete his round, sitting at four under through 15 holes.
He is one of five Americans tied for sixth, with Tony Finau, Keegan Bradley, Charles Howell III and Webb Simpson alongside him.
Defending champion Charl Schwartzel made a decent start to the tournament, posting a one-under 70.