American Bo Van Pelt shot a 5-under 67 on Saturday to take a one-shot lead over compatriot Jason Dufner after the third round of the Perth International.
Van Pelt started the day four shots behind overnight leader Emiliano Grillo and grabbed the lead when the Argentine bogeyed two of his last three holes. The 20-year-old Grillo had moved to 13 under with birdies at the sixth and ninth holes.
Bogeys at 10 and 11 dropped Grillo back into the chasing group and Dufner, who also shot 67 on Saturday, took a share of the lead with five birdies between the seventh and 12th holes.
Grillo reclaimed a one-shot lead with a birdie at No. 12 but Van Pelt finished with four birdies over the last eight holes.