"I was able to lay down in the locker room and get some rest", said the 25-year-old rising star of world golf.
"He made every putt around 20 feet, and was seven under after nine", Phelps said.
Matsuyama and Kisner boast a two-shot cushion over Jason Day after the Australian produced an impressive round of 66.
Phelps saw much that he liked when Spieth, who started on the course's more hard back nine, completed his first nine at par despite fighting his putter.
This is a tough course, but the conditions were flawless, so if the forecasts are right with rain an wind over the next three days, Quail Hollow could become a nightmare.
If Jordan Spieth needs some help with the mental aspect of his game during this pressure-packed week of golf, he knows exactly where to turn.
Stroud was bogey free with three birdies on a golf course he's as comfortable with as Woodland is.
Spieth came into the tournament needing a victory in the PGA Championship to achieve the career Grand Slam.
Marc Leishman chipped in from 85 feet from the back of the green for an eagle on the par 5 10th hole on Saturday.
Sixteen players remained under par.
Jordan Spieth started his quest to complete the Grand Slam saying he did not feel any undue pressure, but his tune changed after a frustrating first round on the greens at Quail Hollow.
The home-state kid from nearby Raleigh playing in his first major as a professional turned in 1 over but tamed the back nine to card a 3-under 68. But he followed a first-round 70 with a 75 on Friday to fall back in the pack. He won the tournament two years ago at Whistling Straits in Kohler, Wisconsin, and he has been in the top three each of the last four years at the 36-hole mark in the tournament.
Three bogeys in his first seven holes derailed that dream. If Wiesberger had gone to 4 over, Scott not only would have missed the cut, his PGA Tour season would have been over.
"This is not the Quail Hollow we have gotten to know over the last 10 years", he said.
That still left the 24-year-old 12 strokes behind halfway leaders Kevin Kisner and Hideki Matsuyama, whose second round of 64 had established a course record for the new layout, just five days after he equalled the course record of 61 at Firestone Country Club to win the WGC-Bridgestone Invitational.
One shot behind him were South African 2010 British Open champion Louis Oosthuizen, Italian Francesco Molinari and American Chris Stroud.
Matsuyama and Kisner were at 8-under 134.