World number one Scheffler put himself into the mix on Friday shortly after being arrested on four counts, including second-degree assault of a police officer, after what he said was a "big misunderstanding" as he tried to enter Valhalla.

Scheffler, who extended his streak to 42 consecutive rounds at par-or-better on Friday, went out in the penultimate group under partly cloudy skies at Valhalla where there is a chance of rain later in the day.

Chasing back-to-back major titles and a fifth win in six starts, Masters champion Scheffler opened with a par.

Schauffele, whose 12-under total matched the lowest 36-hole score in relation to par at a PGA Championship, is seeking his first major title in his 28th start at one of golf's blue-riband events.

LIV Golf's Koepka, looking to become the PGA Championship's first repeat winner since he successfully defended the title in 2019, started the day five shots off the lead and covered his opening three holes in one over par.

World number two Rory McIlroy, eager to snap a 10-year major drought and who arrived at Valhalla among the favourites, began the day seven shots behind Schauffele and was level par after his opening five holes.

Jordan Spieth, seeking to become the sixth player to complete the career Grand Slam of golf's four majors, began the day eight shots adrift of Schauffele and eagled the par-five seventh to get to two under through eight holes.