Min Woo Lee turned in 33 to maintain his three shot overnight lead as he went in search of a first European Tour victory at the 2020 ISPS Handa Vic Open.
The home favourite made three birdies in his first four holes to get to 18 under and lead the way from fellow Australian Marcus Fraser, who also turned in 33.
Kiwi Ryan Fox was then at 14 under through 12 holes, one ahead of amateur Jed Morgan.
In the women's event, Lee's older sister Minjee - a two time winner at 13th Beach Golf Club - was four shots behind leader Ayean Cho - who was 11 under.
Lee announced himself on the European Tour two years ago this week when he made the quarter-finals of the ISPS Handa World Super 6 Perth as an amateur.
After making his professional and Rolex Series debut at the following season's Abu Dhabi HSBC Championship presented by EGA, Lee achieved back to back top fives but narrowly missed out on keeping his playing privileges in his rookie campaign.
He recorded a best European Tour finish as he finished third at the Australian PGA Championship just before Christmas, and is now on course for a first win in just his 19th event.
Lee made a stunning start with a chip-in for birdie on the first but the lead remained at three as Fraser put an approach to six feet.
The par five second was proving gettable and the leading duo both took advantage, with Lee getting up and down and Fraser two putting from off the green after hitting the pin with his second.
Lee almost drove the green at the par four fourth and got up and down to extend his lead to four shots but Fraser trimmed it back to three as he picked up a shot on the par five next.
Fox made his birdie on the second and then drove right up to the side of the green on the fourth, holing a long putt for eagle in a big early move.
A tee shot to eight feet at the par three seventh handed him another birdie and he was five back as he made the turn.
A ten foot right to lefter on the tenth moved Fox to 14 under and it looked like a three horse race was developing.
Morgan bogeyed the fourth but bounced back with birdies on the fifth, sixth, tenth, 11th and 13th.
Jake McLeod was in the clubhouse at 12 under alongside Travis Smyth, who parred his first nine holes.
