By Mark Lamport-Stokes
KOHLER, Wisconsin (Reuters) - Jordan Spieth, looking to carve out another slice of golf history at this week's PGA Championship, delivered another special performance to move into contention before the second round was suspended late on Friday.
The Masters and U.S. Open champion, bidding to claim his third major title of the year and join an elite club, took advantage of relatively calm morning conditions at a sun-baked Whistling Straits by firing a five-under-par 67.
That left the 22-year-old American ominously placed at six-under 138, just three strokes behind Australians Jason Day and Matt Jones, who were both out on the course when play was called off for the day due to the threat of lightning.
World number five Day, still seeking a first major title after several close calls, had completed 14 holes and Jones 12, before strong winds and heavy rain swept across the course.
"There was (weather) trouble lurking there for a second, and then right around the 15th hole, the horn blew and I was kind of glad that we're in," said Day.
"Obviously it's a mess out there, and so I'm just trying to get some rest tonight and go into tomorrow."
English world number six Justin Rose, the 2013 U.S. Open champion, was a stroke back with just one hole remaining.
Swede David Lingmerth, who won his first PGA Tour title at the Memorial Tournament in June, held the clubhouse lead at seven under after carding 70. Also at seven under were Americans Harris English, 15 holes, and Tony Finau, 13.
World number one Rory McIlroy, back in action to defend his PGA Championship crown after five weeks out due to an ankle injury, carded a second successive 71 to sit seven strokes off the pace.
Spieth, who shot 71 in tough afternoon conditions on Thursday, was delighted to play his way into contention, despite struggling with his driver.
"I'm still not pleased with the way I'm driving the ball at all. I'm hitting some quick draws when I'm playing a normal shot," he said.
"But I feel good. I made a couple putts today. With a couple chip-ins for the week, really smart course management and good speed control, we have been able to hold ourselves in there."
Spieth's round turned on an unexpected birdie at the treacherous par-four 18th where he spectacularly holed out for birdie from a tricky lie in a greenside bunker.
Japan's Hiroshi Iwata also took advantage of the receptive conditions and flirted with the first 62 at a major before settling for a record-tying 63 in the second round.
Iwata, who racked up eight birdies, an eagle at the par-five 11th and a bogey, became the 25th player to shoot a 63 at a major as he finished at four under.
Among those still out on the course when play was suspended were first-round leader Dustin Johnson, five under after 14 holes, and former world number one Tiger Woods, four over after 14 and destined to miss a third consecutive major cut.
(Editing by Pritha Sarkar/Andrew Both)