Ryan Palmer walks down the fairway on the first hole during the second round of the PGA Championship golf tournament at Valhalla Golf Club on Friday, Aug. 8, 2014, in Louisville, Ky. (AP Photo/Jeff Roberson)

Louisville , Kentucky – Heavy rain drenched co-leader Ryan Palmer on the opening hole Friday until play was halted in Friday's second round of the 96th PGA Championship at rain-soaked Valhalla.

Course workers were still trying to push standing water off the first green as the American and his playing partners, Irishman Shane Lowry and American Bob Sowards, got there.

Play was suspended moments later due to the downpour, which was projected to dump 1.5 inches of rain on Valhalla by nightfall.

World number one Rory McIlroy, only one stroke off the lead, was among those set to tee off with the early starters in near-flooding conditions over the 7,548-yard layout at the year's final major tournament.

“The course is soft anyway,” McIlroy said. “It was very receptive already.”

Palmer, who shares the lead on six-under par 65 with fellow American Kevin Chappell and Britain's Lee Westwood, resumed the quest for the Wanamaker Trophy off the first tee as sheets of rain pounded the course.

“Heavy rain this morning at ValhallaGolf but the show must go on...” tournament officials tweeted.

But it quickly became apparent that conditions would not allow the competition to continue.

Tiger Woods, a 14-time major champion chasing the all-time record 18 majors won by Jack Nicklaus, was among those set to tee off in the afternoon, as were Westwood and Chappell.

Westwood, with no trophies to show for eight career top-three finishes in majors, birdied his final four holes Thursday to grab a share of the lead, dropping a 40-foot birdie at the ninth to complete his run to the top.

McIlroy, who won the British Open last month for his third major title and won his first World Golf Championships crown last week, was playing alongside his fellow reigning major champions, US Open winner Martin Kaymer of Germany and American Bubba Watson, who won his second Masters in three seasons in April.

“Business as usual,” Watson said of his plans for dealing with the rain threat.

“If we get the call we're going to stop play, then you change your routine a little bit, but we have to do everything the same hoping we're on schedule.”

McIlroy was level for second on 66 with 2013 PGA Championship runner-up Jim Furyk, Italy's Edoardo Molinari, American Chris Wood and Sweden's Henrik Stenson.

Sergio Garcia, a runner-up to McIlroy at the British Open and WGC event, was on 70. He said the rain would help players by making greens more receptive.

“Obviously it's going to make everything a bit easier,” Garcia said.

Garcia is among a handful of the players with the most major starts without a victory in the lineup this week.

Colin Montgomerie, whose Senior PGA Championship victory booked him a spot in the field, has made 71 prior major starts without a win.

Westwood has been in 66 prior majors without a triumph while Spaniard Miguel Angel Jimenez is on 65 such starts, one more than Garcia and three ahead of American Steve stricker. – Sapa-AFP