(CNN) -- Matt Kuchar leads the U.S. PGA Championship after two rounds at eight-under-par as Friday play was suspended by darkness after a second day of fog delays at the Whistling Straits course, Wisconsin.
Kuchar, who shot a second-round 69, is one stroke ahead of Nick Watney and three ahead of a group of seven other players. Tiger Woods was among the 78 players who had yet to finish the second round, which will resume play at 8 a.m. ET Saturday.
Kuchar was among a number of players who could not finish their rounds on Thursday because of heavy fog.
Kuchar told reporters that he suffered a sleepless night waiting to finish his round.
"I just don't feel good when I wake up after only five hours sleep. My body just feels funny," he said.
Whistling Straits has been named as the venue for the 2020 Ryder Cup, and this year's captains Colin Montgomerie and Corey Pavin both struggled to get to grips with conditions.
The veteran pair are locked together on 79, seven-over-par, and seem highly unlikely to make the cut for the final two days.
Friday's play was put back by nearly three hours -- the second successive day that fog has delayed proceedings -- meaning organizers are now facing a race against time to get the tournament completed by Sunday.