Lucas Herbert insists Cameron Smith remains the man to beat even after once again upstaging his superstar LIV Golf teammate to seize the first-round Australian Open lead in Melbourne.

Cashing in on preferred lies from the soggy fairways, Herbert iced his opening round with an eagle three at the last to card an eight-under-par 63 at Victoria Golf Club on Thursday.

The newly crowned NSW Open winner enjoys a one-stroke lead over 2023 Japanese amateur champion Rintaro Nakano and unheralded American Ryggs Johnston.

Nakano and Johnston both posted seven-under 65s at neighbouring Kingston Heath to be tied for second, one shot ahead of a smarting Smith, exciting Kiwi talent Kazuma Kobori, Finn Oliver Lindell and American DP World Tour player Jordan Gumberg, who all signed for six-under 65s at Victoria.

Smith had lashed officials after Wednesday's pro-am for setting up Kingston Heath for American-style target golf, lamenting the "bulls***" softening up of the traditional hard and fast sandbelt layout.

After dropping a shot on his third hole of the morning, the 2022 British Open champion fired up to take out his frustration with officials in a spectacular run of six successive birdies mid-round.

After starting his round on the 10th, Smith conjured a brilliant momentum-saving par from behind a tree on the sixth before closing with his eighth and ninth birdies of the day.

"Yeah, pretty solid. I didn't do really much wrong today," Smith said.

"It was a bit of a slow start, obviously. Getting up so early, just a bit drained there at the start and then I finally woke up.

"The coffee worked and I got on a good roll there through the turn.

"The course is definitely gettable. The greens are soft and there wasn't much wind out there this morning."

The pre-tournament favourite now has three rounds to attack Kingston Heath as he bids to etch his name on the Stonehaven Cup for the first time.

Smith, though, will have to catch an in-form Herbert.

Two weeks after reeling in a four-shot final-round deficit to deny Smith the NSW Open trophy on the Murray River, the Bendigo bomber is again threatening to crash his Ripper GC skipper's party.

The 28-year-old produced a bogey-free round featuring six birdies and his eagle at the ninth, after also starting from the 10th.

Ominously for his chasers, Herbert thought he could have shot even lower.

"There were a lot of shots left out there. You probably feel like that with every round of golf to be fair," he said.

"I didn't really think I'd holed that many putts, just hit it quite nicely, got it into the right spots.

"I probably got a couple of lucky breaks here and there where shots that maybe weren't the best didn't get punished the way they could have.

"You've just got to take your luck when you get it. There's days when you can play really well and nothing goes for you."

But Herbert still sees Smith as "the guy to beat this weekend" after the former world No.2 followed up his second at Murray Downs with another runner-up showing at last week's Australian PGA.

"He's been in some great form. He's obviously finished third, second, second in the last three events," Herbert said.

"He's playing pretty consistently and pretty well. I'll be shocked if he's not pushing me pretty hard on the weekend or I'm not pushing him pretty hard on the weekend to win the Stonehaven trophy."

Smith's Warrnambool-born LIV teammate Marc Leishman relished his return to the sandbelt with a three-under 68 at Victoria, while Min Woo Lee opened with an up-and-down 71 at Kingston Heath to trail Herbert by seven shots.

Defending champion Joaquin Niemann has even more ground to make up after thrashing his club into a tree in disgust during his 73 playing alongside Lee.