Cameron Smith's charge towards a fourth Australian PGA Championship is in top gear after a birdie-laden start to his second round to launch within one shot of the lead.

The Queenslander was eight under at the turn on Saturday, one behind 20-year-old South African Aldrich Potgieter playing in the group ahead of him.

Clubhouse leader Matthew Southgate (67) finished seven under, while Cameron Davis (67) was in a group one shot further back.

Rain meant no play was possible on Friday, officials reducing the $2 million tournament to a 54-hole event that will still conclude at Royal Queensland on Sunday.

Smith burst out of the blocks with back-to-back birdies behind razor-sharp approaches, then added a fourth birdie on the ninth.

His playing partners Jason Day (five under) and defending champion Min Woo Lee (two under) treaded water, but Smith kept pace with new PGA Tour member Potgieter.

He birdied his first three holes, then just missed a short putt for another on the fourth, before adding three more to move to 10 under at the turn.

A bogey on the 10th reduced his lead over Smith to one stroke.

Earlier Lucas Herbert switched into LIV Golf mode to push into contention, admitting the tournament's reduction to a 54-hole shootout will suit him.

The Victorian, fresh off a win at last week's NSW Open, wasn't happy despite shooting a five-under 66.

An eagle on seven thanks to a pinpoint approach was the highlight, Herbert otherwise shaking his head at missed putts and "loose" fairway options on a soggy riverside course.

"Feels weird to sit here and complain about shooting five under, but here I am," he said.

"I'm in the tournament, don't know how far I'll be behind, but somewhere thereabouts."

The top half of the field who make the cut on Saturday will return for an 18-hole shootout for the prize on Sunday.

Herbert partnered Smith, Marc Leishman and Matt Jones in LIV - which means 54 in Roman numerals, in a nod to the three-day teams title they won with Ripper GC this year.

"It's a decent change of mindset in a 54-hole event," he said.

"You play Thursday and you're six back and not paying too much attention.

"But all of a sudden you cancel the round and ... different story.

"I knew I had to shoot a pretty low one today. It sounds easy, but it takes practice to get used to how aggressive you have to be in a three-round event, so there's probably a little bit of an advantage for us."

First-round leader Elvis Smylie was one under through seven holes to be seven-under alongside Ben Eccles, who had three consecutive birdies either side of the turn.