A frustrated Lucas Herbert has suggested golf officials rethink the Australian Open's revolutionary format after enduring a painstaking third round of more than five hours.

In a world first, the Open is being played as a dual-gender tournament but the massive field made for marathon rounds in hot conditions at Victoria Golf Club on Saturday.

Herbert's round took five hours and 20 minutes, with the European and US PGA Tour winner saying the wait time on each hole made it difficult to get into any rhythm.

Following Friday's first cut there were 161 players - 78 women, 71 men and 12 all-abilities golfers - with the packed course proving unforgiving.

Herbert was sitting third until he tumbled down the leaderboard with a triple bogey at the 17th before he finished with a birdie to sign for a three-under 67.

He was reluctant to criticise the new format but said it was particularly slow-going on the challenging course, with officials also forced to ditch the traditional two-ball pairings for the penultimate round in order to move the huge field through.

"I think 77 girls or something made the cut with all the amateurs included so that obviously made things tough creating the draw and it's not an easy golf course out there," Herbert told reporters.

"I feel like it's a tough golf course and I'm one of the best players in the field so for the girls who are not playing the game full time, who have maybe just snuck in through the cut and struggling with their game a bit, it's a brutal test out there.

"It didn't feel like there were many (holes) were we didn't get jammed up ... this is what happens when you have so many people out on the course.

"It's hard when it's stop-start and you don't feel like you can get that rhythm."

Herbert withdrew from last week's Australian PGA Championship midway through the second round with a back injury but said it gave him no trouble in the third round.

The world No.57 was pleased with play apart from some bad luck on the 17th, when his foot slipped while hitting his second with the ball landing jammed against tree.

He chipped out but it landed on a stick and after he "hacked it out" the putt didn't do as expected.

"Every shot got really unlucky - I didn't feel like I did alot wrong for a seven there," said Herbert, who revealed this week he was playing for his mother Meredith, who has recently been diagnosed with breast cancer.

"It was pretty disappointing because I felt I was playing pretty nice and starting to make a move."

Apart from a maiden Open title, Herbert is hunting a British Open start, which is on offer to the top three finishers not otherwise exempt.

"There's a spot in the Open up for grabs and obviously if I finished pretty high up it'll help my world ranking and get that closer to 50 that I need to make the Masters," he said.

"So there's a lot to play for."