Brooks Koepka turned in 30 to open up a three-shot lead during round three of the US PGA Championship at Bellerive Country Club.
The American started the day two shots behind overnight leader Gary Woodland but five birdies on the front nine put the two-time defending US Open champion at 13 under and in pole position for a third Major Championship.
Countrymen Woodland and Rickie Fowler were his nearest challengers, with another American in Kevin Kisner and Australian Adam Scott at nine under.
A charging Tiger Woods, defending champion Justin Thomas, Open Championship winner Francesco Molinari and Ireland's Shane Lowry were then five off the lead.
Woodland did well to make a par on the first after leaving his second short but Koepka put his approach to tap-in range and was just one back.
Koepka hit another brilliant approach into the second to get to ten under and that was good enough to lead on his own as Woodland dropped a shot after putting his second in the water.
Kisner got a tricky lie over the back of the second and he also dropped a shot but he got it straight back from 20 feet on the par three third.
Woodland hit an excellent tee-shot into the same hole to get back into a share of the lead as Koepka made a par.
An 18-foot putt from Koepka on the fifth put him into the solo lead and after both he and Woodland made birdies on the par five eighth, the 28 year old hit an approach to 11 feet on the ninth to get to 13 under.
Woodland then missed his par putt after a poor chip and the lead was three shots.
Fowler went about his business quietly, holing an eight-footer at the sixth and making the most of the eighth to turn in 33, while a hot putter helped Scott make birdies on the third, fifth, sixth and eighth.
14-time Major champion Woods had the enormous galleries going wild as he holed from 15 and five feet on the first and second to jump within four of the lead but a three-putt on the fifth stalled his momentum.
He bounced back with an 11-foot birdie on the sixth and added further gains from seven feet on the seventh and eighth.
Much like Fowler, Italian Molinari was making quiet progress, with dialled-in iron play bringing birdies on the second, eighth and tenth.
Lowry bogeyed the fourth but recovered with birdies on the sixth and ninth, while Thomas followed gains on the first and third with eight consecutive pars.
European Tour Members Pat Perez, Jon Rahm, Charl Schwartzel and Julian Suri were seven under.
