Kevin Stadler finished a marathon day at the top of the leaderboard after rain hit The Barclays in Jersey City.
Stadler's round of seven-under 64 was spread over almost 11 hours as two rain delays took six hours out the day.
Stadley managed to maintain his rhythm through the disruptions as he carded seven birdies through the round, giving him a one-shot lead from Ryan Palmer, Henrik Stenson and Camilo Villegas.
Northern Ireland’s Rory McIlroy and Graeme McDowell both finish on level par, leaving them in a share of 61st place.
Villegas had at one point been on eight-under, but then suffered two late bogies to drop back and hand Stadler the initiative.
However, not everybody had managed to finish their rounds before darkness fell, and Harris English was forced to call a halt to a lightning start to his own round, in which he made up four shots over the opening six holes to sit in a tie for seventh place.
English will now be among those facing an early start today, with another long day on the cards as the tournament looks to make up for lost time.
Those at the top of the leaderboard are looking at a long wait to get going, and then the prospect of not being able to complete their rounds before darkness falls.
"I don't know what time we are going to start," Stadler said on the PGA Tour website.
"It's going to be late, though, but (I) prefer to be on this side where we don't have a marathon day, but we only had to play 18 holes, so it won't take as big of a toll as the other guys, for sure."
Jason Day and Matt Kuchar were two shots off the lead on five under, while Tiger Woods was in a group of seven - including English - on four under.
The world number one missed a birdie putt on the 13th immediately after the first rain delay but then made three straight birdies on his way to a round of 67.
Like Stadler, Woods is now trying to plan ahead for what will be a mixed-up schedule going into the weekend.
"We'll probably get in maybe six or nine holes, somewhere in there," he said.
"But Saturday is going to be the really long one, we are going to get in probably 27-plus, and then be fresh come Sunday."
Among those still needing to finish their rounds are Open champion Phil Mickelson and Masters winner Adam Scott.