Louis Oosthuizen turned in 31 to open up a one-shot lead midway through the third round of the ISPS HANDA Perth International.
The World Number 21 came into day three a single shot off the lead after a brilliant 64 on Friday, and picked up where he left off with five birdies in his first ten holes to get to 15 under, one shot clear of overnight leader Peter Uihlein.
It was a day for low scoring at Lake Karrinyup Country Club, with Romain Wattel seven under for the day through 14 holes to sit three shots off the lead.
Australian Marcus Fraser and Finn Mikko Korhonen were then both in the clubhouse at nine under.
Oosthuizen played a smart approach to birdie the first and after narrowly avoiding the water with his second shot on the third, he came close to chipping in and tapped in for another gain.
American Uihlein also birdied the first thanks to an excellent curling putt but had a three-putt bogey on the second before regaining the shot by taking advantage of the par five next.
Oosthuizen rolled in a 30-foot putt for birdie on the sixth and then nestled his eagle putt on the seventh right up to the hole to open up a two-shot lead.
That would not last for long, though, as Uihlein got up-and-down from the back of the green to birdie the seventh and then put his tee shot on the eighth inside four feet for another gain.
Another brilliant approach to the ninth made it three birdies in four holes for the South African and, although Uihlein did well to save par after finding the trees off the tee on the same hole, he was a shot back.
Frenchman Wattel had a run of four birdies from the second and made three more gains as he searches for a first European Tour win.
Last week's winner Fraser was flawless in his effort of 65, while Korhonen signed for a 66 which included a run of five birdies from the 11th.
Benjamin Hebert was also nine under through 16 holes alongside Jason Scrivener and Richard T Lee.
Local favourite Brett Rumford turned in 39 to slip to eight under with Matthew Griffin and Peter Senior, who were in the clubhouse.