The players were facing a stop-start-stop-start day at the PGA Championship on Friday (local time) as heavy rain swept across Valhalla Golf Club with further thunderstorms expected.
Second-round play was suspended for 45 minutes less than half an hour after the first tee shots of the day were struck and tee times have since been pushed back 50 minutes.
The first stoppage was due to a situation described by organisers as "non-threatening" after greens and fairways were left waterlogged, forcing ground crews to use squeegees in a mop-up operation.
After four days of sunshine and muggy weather at Valhalla, a storm front has moved into the Louisville area and up to an inch-and-a-half of rain has been forecast.
Play was initially halted on Friday (local time) 45 minutes before British Open champion Rory McIlroy was set to start the second round, having opened with a five-under-par 66 on Thursday to sit one stroke off the pace.
McIlroy, the pre-tournament favourite who is bidding for a third consecutive victory on the PGA Tour, is now scheduled to tee off at 9.25am local time (1.25am NZ time).
Englishman Lee Westwood and Americans Kevin Chappell and Ryan Palmer led the year's final major after firing six-under 65s in the first round, though both Westwood and Chappell were among the late starters on Friday.
Palmer, a three-times winner on the PGA Tour, was playing the first hole on Friday when the action was halted.
He later posted a picture of the water-logged first green and tweeted: "Sitting in the shot link tower on 1 watching it rain hard. Waiting it out they are saying. Really??"
While the heavy rain forecast for Friday will leave the greens more receptive to approach shots, it will make the 7458-yard layout play much longer.
Meanwhile, American Ben Crane became the third player to withdraw from the PGA Championship due to back issues when he pulled out before his tee-off time in the second round.
The 38-year-old, a five-times winner on the PGA Tour who was competing in his ninth PGA Championship, had opened with a three-over-par 74 at Valhalla Golf Club.
Crane's exit follows the withdrawals of veteran David Toms and world number six Matt Kuchar, on Thursday, who both cited back issues.
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