Koepka is part of a group of golfers sitting one stroke behind early first-round leader Thorbjorn Olesen. "It's just that indescribable trait that he has to find a way to get it done, find the will to win". So it will be really interesting to see how the rest of the week plays'.
On consecutive holes, Spieth ran long putts some 10 feet by the cup and made bogey. But this weekend at Quail Hollow will be Spieth's only shot at becoming the youngest player to ever do it. Tiger Woods was about six months older than Spieth is now when Tiger completed his own career grand slam at age 24.
"Historically I'm pretty solid with the lead so that was kind of the goal", Spieth said. "On the green was the problem".
Fleetwood, whose previous opening round in a major was a six-over 76 at the British Open at Royal Birkdale - where he used to sneak in as a boy to play - took a far more positive first step at long Quail Hollow with its firm, fast greens.
Alongside Spieth in the feature group were the year's two other major winners, Masters victor Sergio Garcia of Spain and US Open champion Brooks Koepka, an American. He has again peaked at the right time, he said.
It was a contrast from how four-time major victor McIlroy felt in 2015, when he fired a third-round 71 to break his own course record on the way to victory while world number one, saying he needed to show how well he could play. "The PGA is such a great brand, and they do a lot for the game, and a lot of these guys wouldn't be where they are without a PGA professional, and I'm no different. It just comes down to preparation".
Jason Day on his way to a 70 at the PGA today. "But I drove the ball well". "I've proven myself enough over the last nine years of my career". And he has shown skill in wet weather, notably at the 2011 US Open, where he won his first major. But he is fighting to keep the excitement and pressure well managed.
Stroud made the turn at even par and then birdied 10 and 11 before his 20 foot putt on 18 sealed his first round score of 68. "I feel like it takes one hole to recover from a bogey and it takes two to come back from a double".
As bad as Mickelson has been, playing partner and defending PGA Champion Jimmy Walker has been even worse at 7 over through 15.
However, birdies on the next two holes - courtesy of what Spieth described as a "phenomenal" hybrid into the par-five seventh and a "fantastic" wedge to the eighth - repaired most of the damage. "It was good for both of us", McIlroy said. "You know, one shot at a time, as cliché as that is, it's so easy to get frustrated out here with a mediocre shot that ends up in a special spot, or you feel like you have a good chance that never really amounts to anything".
Pre-tournament favourite Rory McIlroy also laboured to a 72 after finding water with his tee shot at the driveable par-four 14th.