Brett Rumford saw his advantage cut to one shot but nobody could catch the overnight leader on a windy second morning of the ISPS HANDA World Super 6 Perth.
The Perth native carded a 64 in round one as he looked to replicate last season's success when he led after all three rounds of stroke play before taking the title on Sunday after the six-hole match play knockout stage.
He was overtaken by Kiradech Aphibarnrat at one point on Friday morning, with Lucas Herbert also moving into a share of the lead, but those two fell back in windy conditions to leave Rumford sat at the top of the leaderboard on eight under before he began his second round.
Herbert's round of 69 moved the Australian to seven under alongside Dane Thorbjørn Olesen, who signed for a 67 to move within one of the lead.
A run of four bogeys in a row meant Thai Aphibarnrat had to settle for a 72 and sit at five under alongside Italian Andrea Pavan, Australians Adam Blyth and Anthony Quayle, and American Sean Crocker.
Aphibarnrat picked up birdies on the 11th, 14th and 15th with Herbert making gains on the tenth, 11th, 12th and 16th as the playing partners joined the lead at the turn.
Olesen has some history around this layout with a victory at the ISPS HANDA Perth International in 2014 and the four-time European Tour winner recovered from a bogey on the tenth with gains on the 11th, 12th, 14th, 16th and first to sit two off the lead.
Aphibarnrat made another gain on the second to briefly lead on his own, but with Olesen making a birdie on the fourth and both Aphibarnrat and Herbert dropping shots on the third, things were tightening up at the top.
There was a two-shot swing on the next as a Herbert birdie after a stunning approach coupled with an Aphibarnrat bogey put the home favourite back in a share of top spot but he would not stay there for long.
Herbert made a double-bogey on the sixth and with Aphibarnrat dropping shots on the fifth and sixth to make it four bogeys in a row, Rumford was back in the solo lead with Olesen as his nearest challenger.
Herbert bounced back with a birdie on the seventh to get back within one of the lead.
Pavan made birdies on the first, fifth, seventh, ninth, 11th, 15th and 17th before dropping a shot on the last to share the lowest round of the day so far with a 66.
Blyth also carded a 66, with Crocker recording a 69 and Quayle a 68.
England's Sam Horsfield, Australians Wade Ormsby and Jack Wilson, and South Korean Yikeun Chang were then at four under.
Thai Pavit Tangkamolprasert made the fifth hole-in-one of the season on the 17th with a seven iron from 201 yards that helped him to three under.