Adam Scott is pledging to keep his foot down after snatching the Australian Open third-round lead in style with another dazzling eagle at the last hole.

Unable to buy a putt his entire front nine, Scott roared to life down the stretch to post a three-under-par 67, converting his share of the halfway lead into a one-stroke buffer.

At 11 under, Scott will duel with Poland's birdie machine Adrian Meronk for the Stonehaven Cup in the final group on Sunday after the two highest-ranked players left in the field opened up a sizeable gap on the chasing pack.

Meronk bagged nine birdies, including six in the first eight holes, en route to a course record-equalling seven-under 63 at Victoria Golf Club to surge to 10 under.

He led Scott by two shots before the former world No.1 birdied the 15th, then eagled the last for the second straight day after knocking his second shot to less than three metres.

Meronk made golf history in July when he became the first Polish player to win on the DP World Tour at the Irish Open and will likely enter the record books again if he crashes his childhood hero Scott's party.

"He's been my role model since I was a child, so that would be also a dream come true for me to play with him," said Meronk.

While Scott is chasing an elusive second Open triumph 13 years after his first, Meronk is bidding to complete an extraordinary comeback.

The 29-year-old was four over par late in his first round on Thursday before cutting loose.

He has since racked up 19 birdies and an eagle in 40 holes.

After starting the day tied with Victorian David Micheluzzi atop the leaderboard, Scott spent much of Saturday trailing after recording eight straight pars and making a mess of the par-5 ninth.

He found the greenside trap with his three-wood second shot, left his next in the bunker and was unable to get up and down to save par.

The bogey dropped Scott to seven under before he finally collected his first birdie after nailing an approach to tap-in range on the 12th to ignite his round.

Australia's only Masters champion says he won't be waiting so long to make his move on championship Sunday.

"If someone starts hot and gets running, then I'm going to make sure I'm running with them," Scott said.

"I'm not thinking that old man par is going to be just winning me the tournament tomorrow."

Min Woo Lee (65) and Haydn Barron (68) share third at seven under, four shots behind Scott.

Micheluzzui had a round to forget, his bogey-filled 73 dropping the Melbourne sandbelt specialist into a five-way tie for seventh at five under, six strokes off the pace.

It was laborious going on Saturday with the course flooded with 161 players - 71 men, 78 women and 12 All-Abilities competitors.

Scott's three-ball at the historic dual-gender Open needed more than two-and-a-half hours to get through their first nine holes.

Lucas Herbert expressed his frustration after taking five hours, 20 minutes for his round of 67 that left the US PGA Tour star at three under and out of contention, eight strokes off the pace.

"It didn't feel like there were many (holes) were we didn't get jammed up," he said.

"This is what happens when you have so many people out on the course."

With officials forced to introduce a second cut after Saturday's round to free up the fairways, only the top 30 players and ties in the men's and women's events will feature on Sunday.

British Open champion Cameron Smith was the biggest casualty of the contentious double cut after his third-round 69 left the world No.3 at one over and in a tie for 47th.