Springfield - British Open champion Henrik Stenson and two-time major winner Martin Kaymer were set to make early second-round charges at leader Jimmy Walker under rainy skies Friday at the PGA Championship.
Play resumed at the 7 428-yard Baltusrol layout under rain and overcast skies, overnight downpours softening a course already hit with more than two inches of rain on Monday, and storms were predicted to dampen the event through the weekend.
Walker, a 37-year-old American, fired a five-under par 65 on Thursday to grab a one-stroke lead over Germany's Kaymer, England's Ross Fisher and Argentina's Emiliano Grillo at the year's last major tournament.
Top-ranked stars faltered on day one as fourth-ranked Rory McIlroy fired a birdie-less 74, his first over-par start at a PGA, and US Open champion Dustin Johnson soared to a 77, only five players faring worse from the field of 156 than the second-ranked American.
British Open runner-up Phil Mickelson, a five-time major champion who won the last PGA at Baltusrol in 2005, rallied for a 71 to match Masters champion Danny Willett, Spain's Sergio Garcia and two-time Masters winner Bubba Watson.
Top-ranked defending champion Jason Day, battling fatigue and illness, was in a pack on 68 while third-ranked American Jordan Spieth opened on 70, birdies on two of the last three holes offsetting a double bogey.
Stenson, who outlasted Mickelson in a dramatic duel two weeks ago at Royal Troon to capture his first major crown, shared fifth on 67 alongside England's Andy Sullivan and Americans Harris English and James Hahn.
Most of the leaders were set for an afternoon tee time.
Walker, off to his best major start by two shots, had only led once before after 18 holes, that in 2011 at the US PGA Houston Open where he settled for a share of 30th. The Texan won the most recent of his five PGA titles at last year's Texas Open.
"On Sunday with a chance to win, it will feel a little bigger, so I look forward to having that chance. It will be fun," Walker said.
Kaymer won the 2010 PGA Championship and 2014 US Open title, but has not won another crown since capturing his second major two years ago at Pinehurst by eight strokes.
"The last few weeks, I've been playing very solid golf. I don't make many mistakes," Kaymer said. "We all want that win. That's what we all play for. Hopefully it will still happen."
Grillo, a rookie, won the US PGA 2015-16 season opener at Napa Valley and shared 17th this year in his first Masters and 12th at the British Open.
Fisher missed only two fairways and two greens in regulation in round one, which he capped with birdies at the par-5 17th and 18th to jump into the hunt.