Phil Mickelson remained on track to become golf's oldest major winner as he held a two-shot lead at the halfway stage of his final round at the US PGA Championship.  

The 50-year-old had ended Saturday's action at Kiawah Island with a one-stroke advantage over Brooks Koepka, who is seeking to win the tournament for a third time in four years.  

Mickelson's slender advantage disappeared with a three-putt bogey at the opening hole, setting the tone for an uneven front nine that saw him record just three pars but still reach seven under.  

The undoubted highlight was a wonderful chip from a tricky greenside bunker by the fifth green that found the cup, delighting a crowd that sensed they could be witnessing history in the making. 

Playing partner Koepka also had his struggles, following up an opening birdie with a double-bogey seven at the second. He sat at five under through nine, the same score as Louis Oosthuizen. 

Abraham Ancer had shown how it was possible to go low on Sunday, carding the best round of the week with a blemish-free 65 that owed much to a fast start.  

The Mexican birdied four of his opening six holes before picking up a further shot prior to the turn, seeing him go out in 31 strokes. While he cooled off on the way back in, it was still an impressive display.  

While his charge came too late to mount a challenge for the tournament, Ancer feels his superb score is a further sign of how he is getting close to making a major breakthrough in his career.  

"I usually like golf courses that are going to be tough, it's not just going to be a birdie-fest and you have to grind it out and have to hit the ball well where you are supposed to," he told Sky Sports.  

"It's not that I don't care about other events, I try to think about every event the same and try to win every time, but I do feel my game is better for golf courses that are tougher."