Seeking to become the first Japanese man to win a major, Matsuyama joined Kisner, who earlier fired a near-flawless 67, at eight-under and two strokes ahead of Australian Jason Day. Thomas was 2 under on the back nine with birdies at 10 and 15 and a routine par at 18, which produced a scoring average of 4.6 Saturday and played as the most hard hole.
Kisner has now held at least a share of the lead after all three rounds this week. Among a group of players tied for fourth at five-under is Italian Francesco Molinari, who equalled Matsuyama's 64 in the afternoon group.
His tee shot on No. 10 went off to the right of the fairway. But unlike his playing partners, he avoided catastrophe on the final three holes.
Unfortunately for him, the ball hit a cart path. Spieth then began to find his putting touch, making two birdies in a row from the eighth and three in a row from the 14th before a double-bogey at the last.
American Rickie Fowler, hoping Quail Hollow will yield his first major championship, is next best in the clubhouse, five shots behind after a 70. Thomas found himself in contention at the U.S. Open two months ago after firing a 63 in Round 3, but he faltered on Sunday.
Meanwhile, Provo's Riverside Country Club assistant professional Chris Moody improved on his 10-over opening round with a 7-over round Friday for a total of 17-over, not good enough to stay for the weekend.
Fox's 66 was the low round of the tournament till that point, and comprised four birdies on the front nine and a further two, plus a lone bogey on the par-four 11th, on the inward nine. Louis Oosthuizen also stood at minus-5 following a 67. He followed with a bogey on the par-4 18th hole to make the turn at 1 over.
Two stars suffered through epic collapses down the stretch Saturday.
Day was starting to look like the player who was No. 1 for so much of past year. I'm going to play the best I can and let's just ride this out.
"I'm just excited about the opportunity".
Day shot a 6-over 77 Saturday, virtually ending his chances at winning his second major this week.
"I like looking at leaderboards seeing what the cut line is and where I am, so I was looking all the way around and it was nice to see my name up there with the big guys".
Expect plenty of drama Sunday as this packed leaderboard works out a new PGA Championship victor.