Schauffele, who held the solo lead after the first two rounds, birdied the final two holes at Valhalla Golf Club en route to a three-under-par 68 that left him at 15-under on the week and level with twice major winner Morikawa (67).

Six players are within two strokes of the leaders entering the final round, including Sahith Theegala, who made five back-nine birdies and sits alone in third place following a 67.

Former Open Champion Lowry, whose 62 matched the lowest score in major championship history, LIV Golf's Bryson DeChambeau (67) and Viktor Hovland (66) are sitting two shots back.

Schauffele, in search of his first major, was fresh off draining a 29-foot birdie putt at the 14th to open a two-shot cushion before encountering trouble at the par-4 15th where his second shot found the long rough, leading to a double-bogey.

Moments later, Morikawa's birdie putt from five feet at the same hole circled right around the cup before dropping in and giving him a one-shot lead.

But Schauffele refused to back down and went on to tap in for birdie at the par-4 17th after his brilliant approach shot from 141 yards settled two feet from the cup before he and Morikawa both birdied the last.

Englishman Justin Rose, who has recorded five consecutive top-15 finishes at the PGA Championship, also moved into the mix with five front-nine birdies on his way to a 64 that left him three shots back of the leaders and in a share of seventh place with Robert MacIntyre (66).

Lucas Herbert (68) is the leading Australian six shots off the pace.

World No.1 Scheffler, who began the day at Valhalla three shots off the lead and having shot even par or better in each of his last 42 official rounds on the PGA Tour, fell back with a two-over-par 73 that left him eight shots adrift.

The reigning Masters champion – chasing a fifth win in six starts – was playing a day after being arrested on four counts, including second-degree assault of a police officer, after what he said called a "big misunderstanding" outside Valhalla.

– Frank Pingue