Top-ranked defending champion Scottie Scheffler fired a three-under par 67 to seize a share of the lead in Thursday's opening round of the PGA Championship.
South African Aldrich Potgieter, Australian Min Woo Lee, American Alex Smalley, Japan's Ryo Hisatsune and Germans Stephan Jaeger and Martin Kaymer also shot 67 to share the lead on a wild day at Aronimink.
Scheffler, a four-time major winner, made five birdies against two bogeys and found himself atop the leaderboard after 18 holes for the first time in a major.
"But is it really a lead when you're tied with six or seven guys?" the American wondered.
"The golf course was pretty challenging," Scheffler said. "I did a good job staying in it mentally on a course that was difficult at times."
Scheffler made birdie putts from 38 feet at seven, 28 feet at 10 and just inside nine feet at 11 to share the lead, then answered a three-putt bogey at 14 with a four-foot birdie putt at 16.
Second-ranked Masters winner Rory McIlroy was frustrated after a 74, having no problems with his blister-hit right foot but plenty with his golf swing.
McIlroy, a back-nine starter, closed with four bogeys in a row and five in his last six holes.
"I'm just not driving the ball well enough," McIlroy said. "It has been a problem all year for the most part.
"That's pretty frustrating, especially when I pride myself on driving the ball well."
An unlikely group did solve Aronimink's trademark undulating greens, including 23-year-old Hisatsune, who made seven birdies, four of them after each bogey in his round in only his fifth major appearance.
"I'm very lucky, especially with a lot of birdies and a lot of bounceback," Hisatsune said. "I'm so happy."
Kaymer, 41, won the 2010 PGA and 2014 US Open but has not had a top-10 major finish in 10 years.
"Didn't make many mistakes. Stayed out of trouble," Kaymer said. "I avoided big numbers and the rest of it was very consistent."
Jaeger birdied five of the first nine holes but struggled on the back nine.
"On the front I hit some fairways and made some nice putts," Jaeger said. "Kept it together on the back."
The only other time two Germans were in the top five of a major round was when Bernard Langer and Alex Cejka shared the first-round lead at the 2001 British Open.
Potgieter, a 21-year-old South African making his sixth major start, made six birdies, including a 43-foot putt at 11, in his PGA Championship debut.
"I definitely left myself in really good positions on the green, made some long putts, so it was nice the putter was warm," Potgieter said.
Lee, a back-nine starter, birdied the fifth and seventh to briefly lead alone before a bogey at the eighth.
"Drove the ball really well," Lee said. "I played pretty solid all day, didn't get myself in too much trouble."
One back on 68 were England's Daniel Brown, who holed out for eagle from 102 yards in the 11th fairway, plus Canadian Corey Conners, Ireland's Shane Lowry and Americans Sahith Theegala, Max Greyserman, 2018 Masters winner Patrick Reed, who had the only bogey-free round, and two-time major winner Xander Schauffele.
American Jordan Spieth, who would complete a career Grand Slam with a victory, fired a 69.
"I feel like I played better than I scored, which is frustrating because you want to get the most out of your round," Spieth said.
'PHENOMENAL SHOT'
Others on 69 included five-time major winner Brooks Koepka, two-time major winners Jon Rahm and Justin Thomas plus South African Garrick Higgo, who was issued a two-stroke penalty for being late to the first tee.
"I wouldn't have been late if I knew I was running late," Higgo said.
Spain's Rahm holed out from the fairway for eagle with a wedge from 101 yards at the second hole.
"What can I say? It was a phenomenal shot," Rahm said.
Two-time major winner Bryson DeChambeau fired a 76 with five bogeys and a double bogey.