Five players were tied on six-under par after a rain-affected, first round at the Atlanta Classic.
Jonathan Kaye, Ryan Palmer, Jonathan Byrd and Parker McLachlin fired rounds of 66 at the TPC Sugarloaf before the rain made conditions tougher for the later players.
Compatriot Kenny Perry joined the quartet at the top after completing 17 holes in heavy rain.
More than an hour's play was lost as the cloudy conditions turned thundery with McLachlin forced to wait to complete his final hole - the course's ninth.
"I actually got cold out there. You get your heart rate going then you sit for 45 minutes or an hour and you get cold," said McLachlin.
"I just tried to stay loose and not think about the shot until it was actually time to tee my ball up and then start thinking about it. Because it's not one you want to sit there thinking about for an hour. It's a tough tee shot."
With few non-Americans in the tournament, the best of the foreign players were Colombian Camilo Villegas who was two off the lead with a four-under 68.
Villegas had an inconsistent round - he eagled the 13th but made three bogeys including one on the par-five 18th.
