After romping through the draw without dropping a set en route to the Australian Open's last eight, Barty enters Tuesday night's quarter-finals a heavy favourite to continue her seemingly relentless march to the title.

Even Pegula accepts as much.

"I feel like Ash is so tactical in everything she does. Really a smart, like perfect kind of tennis player in that way," the American said.

Pegula's coach David Witt agrees.

"She has so many different weapons," he said.

"The slice backhand. She's just super smart on the court. Her serve is probably one of the most underrated, it's really good.

"Whether she has 10 aces or no aces, she moves it around unbelievably.

"Her coming in, she has an all-purpose game where she can come in, volley, the slice. She's very smart on the court on her shot selection."

So smart that Witt says Australia's world No.1 has a knack of dragging her opponents out of their comfort zone.

"Ash tries to bait you into kind of going for shots maybe that you shouldn't go for," he said.

At least Pegula is well practised at gambling.

The 21st seed has spent much of her down time in Melbourne on the card tables of Crown Casino.

So risk-taking against Barty and trying to beat the house should come naturally.

"I've been like six times. I was going every single night," Pegula said of her frequent trips to the casino.

"There literally is a little walkway, like a two-minute walk across to my hotel.

"I just go and play some blackjack.

"It sounds silly, but it got me. It was good for me because it kind of relaxes you.

"But you have to think a little bit in blackjack - what to play.

"It's good because it got me thinking about strategy and all this stuff but, at the same time, it would kill some time and relax me.

"I'm not losing like a ton of money or anything."

Not that she can't afford it.

Pegula is the daughter of the billionaire owners of the Buffalo Bills.

If the Bills' heartbreaking 42-36 overtime loss to the Kansas City Chiefs on Monday's Super Bowl qualifier is any kind of omen, Pegula will fall to Barty in a third-set tiebreaker.

At least now the Bills are done, her parents and friends' full attention can turn to her showdown with Barty for a spot in the Australian Open semi-finals.

"Obviously it's better when you're winning in those positions," she said.

"But it's a cool thing to look forward to. It's fun to get the fans involved because there's not a lot of tennis in Buffalo.

"It's nice that everyone is fired up about me winning and fired up about the game. It makes it really fun."

Barty or Pegula, a quarter-finalist at Melbourne Park for the second year running, will face either fourth-seeded French Open champion Barbora Krejcikova or American Maddison Keys for a spot in Saturday's title match.

Australian Associated Press