Iwata and Spieth shine amid storms
Japan's Hiroshi Iwata equalled the lowest round in major championship history as Jordan Spieth took another step towards an even more impressive feat before bad weather disrupted the 97th US PGA Championship.
Iwata fired an eagle, eight birdies and one bogey to card the 27th round of 63 in the majors, the 34-year-old covering the back nine at Whistling Straits in just 29 to improve on his opening 77 by 14 shots.
That gave the world number 102 a halfway total of four under par, three behind clubhouse leader David Lingmerth - who added a 70 to his opening 67 - and two behind Spieth, who is attempting to becoming just the third player after Ben Hogan and Tiger Woods to win three majors in a season.
Australian duo Jason Day and Matt Jones had reached nine under with four and six holes to complete respectively, with Justin Rose a shot behind on the 18th tee when play was suspended for the day as a violent thunderstorm whipped through the course.
"I'm glad that we are in," said Day, who hit his approach to the 15th green seconds before the siren sounded. "It can get a little dangerous out there. It's a good idea to come back in the morning."
Rose admitted it was going to be "a bit of a drag" to face a 5am alarm call for the scheduled 7am restart on Saturday, but joked: "I opened my big mouth to the boys I was playing with and said the end was in sight. Thirty seconds later they blew the horn, so my name was mud walking up the 18th."
Spieth began the day five shots off the pace and tipping playing partner Rory McIlroy to make a move up the leaderboard, but it was the Masters and US Open champion who took advantage of the ideal conditions to shoot 67.
Defending champion McIlroy double-bogeyed the 18th hole, having begun on the back nine, and chipped in for an eagle on the second in an eventful second consecutive 71 to finish two under par.
"We are free-rolling now," Spieth joked after making the cut in the US PGA for the first time at the third attempt. "I'm just happy to be back in contention and position. If I'd had a bit of a lull today it would have been too hard to make up.
"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.
"But in order to keep shooting the rounds like today, I'm going to need to drive the ball a little bit better and make a few more putts, which are really the two keys for me this weekend, b ecause it's just going to get more challenging with pin locations and firmness of greens."
After starting from the 10th, Spieth and McIlroy were both one under par for the day after eight holes before Spieth holed out from a greenside bunker on the 18th for birdie and McIlroy mishit two chips from left of the green for a double bogey.
It was the 16th time this season Spieth had chipped in and after adding three more birdies on the back nine, the 22-year-old said: "It's arguably the best of the year given the position it was in. It was a great spark to get things going, get a little confidence, a little pep in my step."
As well as winning the Masters and US Open and two other PGA Tour titles, Spieth was one shot outside the play-off at the Open and has recorded eight other top-10 finishes in 2015.
" I feel good," he added. "I've got a chance to win a major Championship. Just thinking about that gets you enough adrenaline that there won't be any issues.
"I noticed last year for the first time I felt fatigue and felt like I had overworked and kind of burned out the end of the year, as we had to go through the four play-off events without a break and then into the Ryder Cup. This year I've done a better job of when I take time off, when you limit the practice coming back, how to prepare.
"As far as mentally in this position, the way the year's gone, I approach each event as if it's the only event of the year when I stand on the first tee. That gets me through it. I'm sure at the end of this year, it will be nice to sit back and hang the clubs up for a couple weeks, but until then we have got a lot to play for."
Iwata needed to birdie the 520-yard 18th to shoot the first 62 in major history, but in the end did well to save par from short of the green.
Speaking through an interpreter, Iwata said: "The course conditions are very different from yesterday and today. Yesterday the wind was so strong and the green was really hard that I can't stop the ball with my wedges.
"On the back nine, after making a birdie at number 13, I was thinking that I'm going to shoot 27. I wish I could have just shot one less!"
Weather warnings were posted on the course at 16.30 local time and play was finally suspended an hour later, with the decision soon taken to call off play for the day as strong winds and rain battered the course.
Former world number one Tiger Woods was four over par with five holes remaining, two shots outside the projected cut and in danger of a third straight early exit from a major for the first time ever.
The 39-year-old then announced he had committed to play in next week's Wyndham Championship in a last-gasp bid to qualify for the FedEx Cup play-offs.
It later emerged that Jamie Donaldson had been forced to withdraw from the tournament due to a recurring back injury.
The 39-year-old Welshman, who carded a first-round seven-over-par 79, called it quits after completing 15 of his 18 second-round holes.
The world number 38 was nine-over-par overall and after carding three birdies, three bogeys and one double bogey on Friday.