Brendan Steele surged into a two-shot lead at the Texas Open before darkness brought an early end to the first round on Thursday.
The American birdied eight of his 13 holes before the round was suspended, with inclement weather causing an earlier delay.
Steele started on the back nine and birdied four of his first five holes, before a hat-trick from the first to the third put him in the lead.
Charley Hoffman managed to finish his round, a six-under 66 seeing him sit second.
Australian Stuart Appleby completed his round with five-straight birdies to be in a tie for third alongside Peter Malnati at five under.
Steele has missed the cut at his past two events but the 2011 champion showed much better form in the opening round to take control of the PGA Tour event.
The tournament had been delayed for several hours earlier in the day, leading to several players being unable to complete their rounds.
Brandt Snedeker (through 14), Patrick Reed (13) and Freddie Jacobson (11) were among them, sitting at four under along with Steve Flesch - who finished with a 68.
Hoffman was left to lament a late bogey - at the 17th and his only one of the round - but he is nonetheless well placed.
Appleby produced an incredible finish to move into contention, with a streak of birdies from 14 to 18.
Defending champion Jimmy Walker made a poor start to his defence, firing a three-over 75 to be well off the pace.
Englishman Luke Donald is three under through 14 and Branden Grace is a further two shots back after playing 13 holes.