Kohler - Jordan Spieth stepped up his bid for golf history on Friday, firing a second-round 67 that put him in the hunt for a third major title of 2015 at the weather-disrupted PGA Championship.
Spieth's six-under total of 138 put him one stroke behind clubhouse leader David Lingmerth, who had eight birdies, four bogeys and a double-bogey in a roller-coaster of a two-under par 70.
The Swede got as low as eight-under, and his 36-hole total of seven-under 137 gave him the outright lead when he walked off the course.
But Lingmerth's prediction that he'd be caught proved true, and Australians Jason Day and Matt Jones were both at nine-under on the course when thunderstorms swept across Whistling Straits on Friday evening, halting play for the day.
England's Justin Rose was eight-under with one hole to play when the horn sounded, while Americans Harris English and Tony Finau were both at seven-under.
Organizers said the round would resume at 07:00 (12:00 GMT) on Saturday. It was a fittingly chaotic end to a day that saw five players briefly hold at least a share of the lead.
"Obviously, I opened my big mouth to the boys playing with us, I said, 'The end is in sight, and 30 seconds later they blew the horn,'" Rose quipped.
"So my name is mud all over here."
Despite the hassle of returning to finish, Day wasn't disappointed that the round was stopped.
"I was kind of glad that we're in," he said. "Obviously it's a mess out there, and so I'm just trying to get some rest tonight and go into tomorrow."
Spieth, who started the day five off Dustin Johnson's lead at six-under, had six birdies and one bogey.
After victories in the Masters and US Open, the 22-year-old Texan has a chance to join Ben Hogan and Tiger Woods as the only men to win three major championships in the same year.
After teeing off on 10, Spieth birdied 11 and bogeyed 12. A birdie at 16 was followed by an improbable birdie at 18, where he holed out from a bunker.
"All in all, I felt like I scored the way I played," said Spieth, who was less than satisfied with his driver.
"My ball striking into greens is pretty good. I made a couple of putts today. With a couple of chip-ins for the week and really smart course management and good speed control, we have been able to hold ourselves in there."
With Rory McIlroy's world number one ranking in his sights, Spieth separated himself from the Northern Ireland star.
McIlroy posted a second successive 71 on Friday that left him five shots off the pace in his bid for a second straight PGA Championship crown.
His round was marred by a double bogey at the par-four 18th, where a beautiful drive was followed by a second shot into the rough.
He got back on track with his own unlikely break -- an eagle at the par-five second hole where he chipped in from the front of the green.
But McIlroy played the remaining holes in even par, unable to keep pace as Spieth picked up three birdies on his inward run.
"I didn't putt as well as I would have liked," McIlroy said. "It would be great to hole a few more putts, because I feel like I'm giving myself plenty of chances."
British Open champion Zach Johnson, the third player in the "super-group" along with Spieth and McIlroy, endured another frustrating day that had him headed for an early exit.
He opened with three straight birdies, but finished with four birdies and four bogeys in a 72 that left him three-over for the tournament and outside the projected cut line.
"It wasn't very good," he said.
- Iwata joins 63 club -
A hot, humid morning saw plenty of birdies on the par-72, 7,501-yard Straits course hugging the shores of Lake Michigan.
Japan's Hiroshi Iwata matched a major championship record with a nine-under par 63 -- the 27th time a player has shot 63 in a major. Two players -- Greg Norman and Vijay Singh -- did it twice.
Iwata had eight birdies and an eagle with one bogey to build a four-under total of 140 for 36 holes.
Former world number one Tiger Woods, however, wasn't making any headway.
The 14-time major champion was one-over through 13 holes and looking set to miss the cut at a third stright major.
-9 Jason Day (Australia) 14 68, Matt Jones (Australia) 12 68
-8 Justin Rose (Britain) 17 69
-7 Harris English (U.S.) 15 68, Tony Finau (U.S.) 13 71, David Lingmerth (Sweden) 18 67 70,
-6 Jordan Spieth (U.S.) 18 71 67, Scott Piercy (U.S.) 18 68 70, J.B. Holmes (U.S.) 14 68, Russell Henley (U.S.) 17 68, Brendan Steele (U.S.) 18 69 69
-5 Dustin Johnson (U.S.) 14 66, Danny Lee (New Zealand) 13 68, George Coetzee (South Africa) 18 74 65
-4 Hiroshi Iwata (Japan) 18 77 63, Anirban Lahiri (India) 13 70, Marcel Siem (Germany) 18 70 70, Paul Casey (Britain) 16 70, Charles Howell III (U.S.) 18 70 70, Hideki Matsuyama (Japan) 18 70 70, Matt Kuchar (U.S.) 18 68 72, Brandt Snedeker (U.S.) 17 71, Billy Horschel (U.S.) 18 72 68