Why wouldn't he?

The 25-year-old was on the verge of becoming a fire hazard at Royal Pines, where he ended the day at 17-under to take a three-stroke lead into Sunday's final instalment.

While most expectations fell on overnight leader Marc Leishman, or Spanish great Sergio Garcia, it was the relatively unknown Zunic that was turning water into wine on the Gold Coast.

He birdied seven of the first nine holes to be out in 29 (par 36) and at that point, looked as if he could make birdies if he tipped his clubs in the lake and went around with a couple of fence posts.

Then, a moment of relative calm.

Holes 10-12 returned pars as Zunic caught his breath, before the show started all over again as he made birdies on 13, 14, 15 and the par-three 16th.

A birdie-birdie finish would have seen him trash the record books.

The previous best round in an Australian championship was scored by Ernie Els, who rattled off a 60 at the 2004 Heineken Classic at Royal Melbourne. Nobody on the European Tour (who co-sanction this event) has gone below 60 in its history.

Call it white line fever but Zunic blinked, even if he later contended the mistakes weren't major.

A bogey on the 17th ended that particular dream, before a double on the par-four 18th left him vulnerable going into Sunday, where he leads rising star Cameron Smith by three shots.

"It is tough [not to think about the score] but to be honest, I didn't have much of a problem with it,” Zunic said.

“There might have been one time when I thought, 'I'm going pretty good today', that might be a possibility.”

"But I quickly got back to the moment I was in and that helped me to continue to make birdies once I turned going into the back nine.

“It is tough but I didn't have any problems just staying in the moment and taking every shot as it comes.

"It was a bit of a flash that round. I can't remember bits of it.

“I'm just really happy with today, obviously the way I played all day was what I know I was capable of doing.

“To come out and do that in tournament mode is awesome."

The end result was an equal course record of 64, nothing to scoff at but a slight disappointment given the way he had been playing for all but the final two holes.

Zunic said he had already erased those from the memory.

"What two holes?” he said.

“I'm just thinking of 16 good holes.

“That's all I see in my mind.

“I played unbelievable golf for 16 holes.

“If you had told me I'd have a 64 today, I would have taken it. 

"I didn't really do much wrong the last two holes.

“I still stuck to my processes and that's all you can do."

Smith looks the clear danger.

The 24-year-old Queenslander, who has already won an event on the PGA Tour in the US, overcame a water hazard on seven to keep his nerve and finish within striking distance.

His back nine was rock solid as he carded a nine-under 67.

World No.13 Leishman started the day as joint leader on 12-under but couldn't get anything going as the wind picked up.

He finished two-over for the day to be tied for fourth, seven shots off the pace.

"Yeah, it was a tough day,”  Leishman said.

“Actually played quite well early and just couldn't make any putts unfortunately.

“Bogeyed 12, doubled 13. Frustration got the best of me on the 13th tee there,".

"Got one birdie coming in, a couple good par saves.

“So disappointing but I think I'm, what, seven or eight back going into tomorrow.

“Need to go out and attack and try and shoot as low as I can."

Play will start early on Sunday, with the final groups to tee off at 8am to try and beat the forecast storms in the region.