We spent much of Saturday awaiting the moment whereby Phil Mickelson peeled back his sunglasses to reveal an alter ego. Or Phil Mickelson in his pomp. Just weeks short of his 51st birthday, 16 years after the one and only time he has lifted the Wanamaker Trophy, Mickelson was making a mockery of the US PGA Championship. In what is typically a tame and non-tribal environment, Mickelson was vociferously roared on from shot to shot. Victory in South Carolina would be the greatest of his career and render Mickelson the oldest major champion of all time. Phil brought the thrills and looked unstoppable. Mere mortals wilted as Mickelson stood firm. When holing out for a birdie at the 10th, the five-time major winner had completed an 18-hole stretch in nine under par. Mickelson was five clear. Kiawah Island’s Ocean Course, remember, is depicted as among the most ferocious of major venues. How brittle the mutual affections between golfer and championship venue can be. Mickelson would have known to beware alligator-infested waters. The finding of precisely that from the 13th tee hauled him back towards a merciless pack. And yet, as the dust settled on an enthralling day three it was Mickelson who still sat atop the leaderboard. His 54 hole advantage is one, at seven under par, from Brooks Koepka. Louis Oosthuizen is five under. Mickelson’s basic Saturday score, 70, barely depicts an afternoon of high octane drama. Koepka’s touch here is somewhat incredible in itself. The last time the double US PGA winner completed four tournament rounds was from 28 February, since which point he has undergone knee surgery and missed two cuts from as many starts. Koepka, though, will inevitably draw inspiration from the fact it is Mickelson he is seeking to swat aside. Those with more recent history of major glory present another level of challenge. For so long, it was easy to forget Mickelson had started day three in a share of the lead, at five under par, with Oosthuizen. Mickelson birdied the 2nd and 3rd – the latter came after an outrageous approach from a fairway bunker – and steadied himself from the unwanted attentions of a drone at the 4th to save par. Further shots were picked up at the 6th and 7th. Mickelson stood in the middle of the 9th fairway with 166 yards to the pin and a four stroke lead. His first properly loose shot of the day didn’t result in damage as Mickelson rescued a four from a greenside sand trap. Mickelson’s failure to take advantage of the par five 11th did not look altogether significant until he found sand from the tee at the next. A first dropped shot in 21 holes was the upshot, meaning Mickelson led Oosthuizen – who had just birdied two in a row – by two. Even then, Mickelson’s ball was a half roll from toppling in for par. Oosthuizen’s response to catching sight of Mickelson once more was to carve his subsequent tee shot into the hazard. Mickelson duly, and in keeping with so little that had come before, followed the South African into the pond. After a Mickelson double bogey, his advantage was one; now over Koepka and Oosthuizen. Mickelson played a towering iron to within 8ft of the cup at the 14th but watched his birdie attempt stay agonisingly above ground. Mickelson’s wild drive at the 16th, delivered into sand dunes as Koepka was joining him at seven under from the green, added fuel to the fire of a crumbling fairytale. Nonetheless, Mickelson played his closing three in level par; Koepka did likewise but bogeyed the last. It would be a stretch to claim momentum is Koepka’s now. Bryson DeChambeau signed for a 71 as leaves him at minus two. The Californian may come to seriously rue a double bogey at this penultimate hole but he remains part of the US PGA discussion. So, too, Joaquín Niemann and Gary Woodland, who have matched DeChambeau’s total. Branden Grace and Christiaan Bezuidenhout sit at minus three, one shy of Kevin Streelman. Paul Casey is one under, where he has Im Sung-jae for company. Jordan Spieth’s 68 hauled him back to level par. The Texan’s attention, though, was taken up by Mickelson’s heroics. “It’s Phil, right? It’s theatre,” said Spieth. “The guy’s got four good rounds on any golf course in him and no one would bet against that. It’s pretty incredible. He’s one of the best to ever play the game.” Few could dispute that; it is this sudden return to such prominence that has captivated the golf world. Eighteen holes stand between Mickelson and the making of history. He couldn’t… could he?