Hideki Matsuyama and Chris Stroud shared the lead at the turn as the US PGA Championship was set up for a dramatic finish at Quail Hollow Club.
Both players were looking to make it back-to-back wins after the Japanese won the WGC-Bridgestone Invitational and the American the Barracuda Championship last week.
They both also picked up a single shot on the front nine to sit at seven under, a shot clear of American duo Kevin Kisner and Justin Thomas.
European Tour Members Francesco Molinari, Louis Oosthuizen and Patrick Reed along with American Rickie Fowler were then at five under.
Matsuyama missed a makable birdie opportunity on his first hole but that was better than Thomas, Stroud and Oosthuizen who all dropped a shot on the opener.
Thomas then holed from 16 feet on the second to get back to five under but Matsuyama missed a six-footer and Kisner had a two-shot lead.
Thomas made another bogey on the third to drop back but Stroud hit an excellent tee-shot into the fourth and the leader's advantage was down to one.
Matsuyama hit his tee-shot into the sixth to nine feet for a birdie and when he took advantage of the par five seventh, he was in a tie for the lead.
Stroud missed the green on the same hole and with Thomas and Oosthuizen both also making the most of the next, the leaderboard was tightenting up at the top.
Kisner had looked totally unflappable to this point but he found the water on the seventh to surrender a bogey and all of a sudden Matsuyama was the solo leader at seven under.
Stroud put an approach to eight feet on the eighth to bounce back from his dropped shot and when Thomas holed a 36-footer ahead on the ninth, there was a three-way tie for second.
Stroud was the man to break out of that pack with a stunning approach to the ninth and he was tied for the lead at the turn.
The group at five under was beginning to swell as Fowler made four birdies in a row from the 12th after turning in level par while Reed birdied the tenth after making four birdies and two bogeys on the back nine.
Molinari also turned in two under and after a bogey on the tenth he made gains on the 11th and 12th.
Gary Woodland, Graham DeLaet and Grayson Murray were three under.