Jordan Spieth and Rory McIlroy carded contrasting opening rounds of 72 as Spieth aims to become the youngest player to complete a career grand slam in the 99th US PGA Championship.
Spieth's dramatic Open victory at Royal Birkdale means another at Quail Hollow would see him join Gene Sarazen, Ben Hogan, Gary Player, Jack Nicklaus and Tiger Woods in having won all four majors.
But the 24-year-old had to birdie two of his last three holes to finish one over, five shots off the lead shared by Denmark's Thorbjorn Olesen and American Kevin Kisner.
In contrast, pre-tournament favourite McIlroy - who has won two PGA Tour events at Quail Hollow - was two under par for 12 holes before dropping three shots in the next two holes.
McIlroy bogeyed the 13th after a clumsy chip and then made a complete mess of the short par-four 14th, pulling his three-wood tee shot into the water and then fluffing his pitch following a penalty drop on his way to a double bogey.
The 28-year-old also failed to birdie the par-five 15th and said: "I wish I could have those three holes back, but apart from that I played nicely and I'm still in it."
US Open champion Brooks Koepka was a shot off the lead along with fellow Americans Grayson Murray, Gary Woodland, Chris Stroud and DA Points, with England's Paul Casey another shot back on two under.
After starting from the 10th and covering the back nine in level par, Spieth bogeyed the first and three-putted both the fifth and sixth from just off the green.
But he repaired most of the damage with birdies on the next two holes, courtesy of what he described as a "phenomenal" hybrid into the par-five seventh and a "fantastic" wedge to the eighth.
"Historically I'm pretty solid with the lead so that was kind of the goal," Spieth said. "It's much easier when you are on the front page of the leaderboard than it is coming from behind.
"Given it's the first round I know I'm still in it, but I know that tomorrow's round becomes that much more important to work my way and stay in it. I've got to make up ground.
"If I'm five back at the start of the day, I've got to be less than five back after Friday to really feel like I can play the way this golf course needs to be played and still be able to win.
"I drove the ball well today. If you told me I was going to hit my driver the way that I did today, I would have definitely thought I shot a few under par. I can't putt any worse than I did today."
Spieth had insisted on Wednesday that he had no "burning desire" to surpass Woods as the youngest grand slam winner and was "freerolling" this week, but added: "I don't think I was as freerolling as I thought I would be, as you can tell by some frustration.
"If I would have shot one over and didn't strike it well and everything was average, it would have been fine. But when I had the chances that I had and I just couldn't get the ball to go in on the greens, that is when I get the most frustrated I can get out there."
Olesen had only played 13 majors before this week, but was ninth in the Open in 2012 and finished sixth on his Masters debut the following year.
The 27-year-old was also 10th in last week's WGC-Bridgestone Invitational and carried on where he left off on Sunday with a round containing six birdies and two bogeys.
"Last week I was struggling a bit the first two days with my driving but then I sorted that out over the weekend and started making a lot of birdies," Olesen said.
"I've had a couple of top 10s in majors and I feel like I've learned a lot over the years. I feel like I'm better prepared to be in contention over the weekend and have a chance to win."
Playing alongside McIlroy, Rickie Fowler recovered from a triple-bogey seven on the fifth to shoot two under par, with world number one Dustin Johnson a shot behind.
In contrast, defending champion Jimmy Walker slumped to an 81 and Phil Mickelson and Ernie Els struggled to rounds of 79 and 80 respectively in their 100th major appearance. Mickelson failed to card a single birdie as he registered his highest score in the US PGA.