Torrential rain forced play to be suspended after just 20 minutes in the second round of the 96th US PGA Championship on Friday.
Play had got under way on schedule at 7:30am, but the first group of joint leader Ryan Palmer, Ireland's Shane Lowry and Bob Sowards were still on the first green when it was called off.
Two members of the greenkeeping staff at Valhalla had been attempting to clear water off the green, but that proved an impossible task as the rain intensified.
The forecast for the rest of the day was also not promising, with Tiger Woods predicting on Thursday that, as one of the later starters, he might not complete his second round until Saturday.
Palmer shared the lead with compatriot Kevin Chappell and England's Lee Westwood on six under par, with world number one Rory McIlroy a shot behind alongside Henrik Stenson, Chris Wood, Edoardo Molinari and Jim Furyk.
Woods, who had declared himself fit just days after withdrawing from the final round of the WGC-Bridgestone Invitational with more back problems, had struggled to an opening 74 on a day when 53 players broke par.
The rain eased sufficiently for play to resume at 8:35am, with Palmer completing a par on the first to remain six under but Lowry carding a bogey five to drop back to two under.