Louis Oosthuizen stormed clear at the South African Open on Saturday, dominating the third round at Randpark Golf Club as Charl Schwartzel faltered.
Oosthuizen, returning to the competition for the first time in eight years, led the tournament through 18 holes before falling back to third, behind the rampant Schwartzel, on Friday.
It was Oosthuizen's turn to seize the initiative once more as the weekend began, the former Open champion building a three-stroke lead with a four-under 67.
That advantage could have been more commanding had Oosthuizen not bogeyed the 16th as he cruised down the back nine.
"It was tough again but I played well," he said. "I hit a few bad drives where I was left but, on 12, I fixed it quickly and then rolled the putter nicely.
"I've been putting well for a long time now. [On Friday,] I couldn't make anything and today the makeable ones went in.
"It's 18 more holes of good golf [to win] and I just need to take one shot at a time."
Oosthuizen profited from the ordinary form of the two players he had trailed, with Schwartzel one over for the day as Madalitso Muthiya battled to a par round.
Schwartzel bogeyed two of the first three holes and could not recover, opening the door for Oosthuizen, while Muthiya had two double-bogeys as well as a bogey and five birdies in a wildly inconsistent round.
They were joined in a tie for second by Matt Wallace, who was three under for the day despite his own rollercoaster back nine.
Ernie Els matched Wallace's 68 to join a clutch of eight players joint-fifth.