Four years and a day after winning the last of his four major titles in the 2014 US PGA at Valhalla, McIlroy gave himself a glimmer of hope with birdies on the 10th and 11th, only for the 29-year-old to double bogey the next after a wayward drive.
Koepka defended his US Open crown in June, the first back-to-back US Open victor since Curtis Strange in 1988-89. Even more than the British Open. It's long, soft and bland, and the 100th PGA probably deserved something better.
Most notably, the world number 50 missed a 20-foot putt for eagle on the par-five 17th and then saw his four-foot birdie attempt slide by.
And there is quite the band of Clydesdales ready to race to the finish. In the lead at 12 under, Koepka is supplying the rolled-up sleeves and the kind of blacksmith arms that would've left Arnold Palmer's arms on the wrong side of a before-and-after ad. At one point, the two-time U.S. Open champion looked to be running away with this championship.
Second-ranked defending champion Justin Thomas had five morning birdies against a lone bogey to conclude a 65. 14 and 15 brought him back.
But in his wake are some other heavyweights. "Every shot's so important out here, and you need to be able to play well". No. 7 Jon Rahm and No. 9 Rickie Fowler, each at 9 under, are hungry for their first major. "Tomorrow is going to be a long day for a lot of us".
In the hunt: Jason Day. Day is also a two-time victor this year. "So just try to get to the top of the leaderboard and work from there". Instead, he was the 15th player to shoot 63 in the PGA Championship.
Now, if he can only get the putter to cooperate.
"It's good but it's also disappointing at the same time", admitted Woods after his third round.
Aug 11, 2018; Saint Louis, MO, USA; Tiger Woods greets fans as he walks to the 2nd tee during the third round of the PGA Championship golf tournament at Bellerive Country Club.
A crowd of reporters laughed at Koepka's retelling, but it's clear this is one golfer who doesn't often find real or imagined slights amusing.
"I said to him down maybe the first hole or second hole, 'Mate, this is a real privilege for me to be playing with you, because 18 months ago I was on a mini-tour and I worked really hard to where I got to now.'" - Matt Wallace on his excitement at playing alongside Jordan Spieth. Frankly, everything about this golf tournament in the St. Louis Cardinals' backyard was supposed to be for the birds. The previous three majors were more like a microwavable Stouffer's meal.
The feat has never been culminated at a PGA but it has been completed at Bellerive - South Africa's Player when he won the 1965 US Open. The third round was marred by a botched course setup and Mickelson's antics on the 13th green.
Spieth refused to acknowledge he's out of it entering Sunday's final round. "I was just trying to make the thing". And Koepka didn't even tee it up because of a wrist injury. The kicker came at the par 5 17th.
Woods, whose earlier charge on the easier front nine raised the massive gallery's excitement to fever pitch, was among a logjam of six trailing by four shots.
And Woods knew the putt was bad.
"I just wish I could have got myself a couple more shots closer to the lead but there aren't a lot of guys up there in front of me".
But then the golfing gods gifted this marathon Saturday out of left field and left us all with a Sunday at colorless and faceless Bellerive that could be the most memorable golf event of the year, and of many years to come.