Louis Oosthuizen backed up his pre-tournament favourite status at the Perth International by opening up a three-shot lead with just one round remaining.
The South African spoke of the need to build momentum before the Masters in April and a five-under-par third round of 67 put him on course for a first European Tour victory in two years at 15 under.
Oosthuizen was just a shot off the lead at the halfway mark following a sublime second round of 64 and took charge in great scoring conditions on moving day at the Lake Karrinyup Country Club.
The seven-time European Tour winner opened up a five-shot advantage on the back nine, but dropped shots at the 16th and 17th on Saturday after an incredible run of 40 holes without a bogey.
World number 21 Oosthuizen birdied two of the first three holes and made another three gains on the front nine to top the leaderboard.
Back-to-back birdies at 14 and 15 strengthen the 2010 Open Championship winner's grip on the tournament, but two late blips gave his rivals hope heading into the final day.
Peter Uihlein started the day with a share of the lead alongside Perth native Brett Rumford after the American was the sole leader following the first round, but a 71 saw him slip back to 12 under.
A triple bogey six at the 12th proved to be costly Uihlein, who also finished with a bogey after dropping a shot at the second.
Romain Wattel is level with Uihlein on 12 under following a sparkling seven-under 65, surging into contention with four birdies in a row from the second and another three after a disappointing 71 on Friday.
Jason Scrivener leads the Australian contenders on 11 under following a 69, while Rumford's hopes of a victory in his home city were hit by a one-over 71 which leaves him five shots off the pace despite back-to-back eagles at 14 and 15.
Rumford's compatriot Marcus Fraser is one of five players on nine under following a magnificent third round of 65 a week after he won the Maybank Championship Malaysia.