Ben Crane carded a bogey-free 62 that included six birdies and an eagle on the par-five 15th to be clubhouse leader when rain ended play early at the US Bank Championship in Milwaukee.
Kenny Perry, who has finished in the top 10 in four of the last five years here, including a win in 2003, fired a seven-under-par 63 to be one stroke off the lead after completing the first round at the Brown Deer Park Golf Club.
Chris Smith, Jeff Sluman, a two-time winner of the event, and Jerry Kelly are tied for third at six under.
Perry, coming off a strong finish on the Old Course at St Andrews, where he tied for 15th, is chasing his third win of the season.
Perry, ranked 10th in the world and sixth on the money list, is the top player at a tournament missing the game’s big names.
Open champion Tiger Woods is not entered, nor are Vijay Singh and Phil Mickelson.
Paraguay’s Carlos Franco, who has just one top-10 finish this year, is back to defend his title and was at even par after four holes when play was suspended.
After a pair of rain delays, play was abandoned for the day with 95 golfers yet to finish the first round.