Novak Djokovic has won all nine of his Australian Open semi-finals and is not ready to let Tommy Paul ruin his unblemished record on Friday as he closes in on a 22nd Grand Slam crown.

The Serb, who won his first Slam at Melbourne Park in 2008, struggled physically in the early rounds this year with a hamstring injury.

But straight-sets thrashings of Alex de Minaur and Andrey Rublev for the loss of just 12 games ominously signalled that the favourite is back to his best for the semi-finals.

Should he beat the unseeded American Paul on Rod Laver Arena, he will face either third seed Stefanos Tsitsipas or Russian 18th seed Karen Khachanov as a final roadblock to a 10th Australian Open title on Sunday.

Djokovic has extra motivation to go all the way and equal Rafael Nadal's 22nd Grand Slam crowns after missing last year's event when he was deported over his Covid vaccination stance. In his absence the Spanish great won.

"I always try to give my best, particularly in Grand Slams, because at this stage of my career those are the tournaments that count the most," said the 35-year-old.

"But you could say that there is something extra this year. You could say because, yeah, the injury, what happened last year, I just wanted to really do well.

"So far I have a perfect score in Australian hard courts, in Adelaide (which he won) and here. I've been playing better and better. I couldn't ask for a better situation to be in at the moment."

With Djokovic on a 26-match win streak at the Australian Open -- equalling Andre Agassi's Open-era record at the first Grand Slam of the year -- the 35th-ranked Paul is a heavy underdog.

The 25-year-old is a surprise semi-finalist, making this far at a major for the first time on the 14th attempt.

"We never played a match against each other. Obviously he's pretty comfortable here in Australia," Paul said.

"It's going to be a challenging match, but I'm playing some of my best tennis, so it's a good time."

Djokovic said he had been monitoring the American and would not underestimate the challenge.

"He's been playing probably the tennis of his life," he said. "Very explosive, very dynamic player. I think he can hit all the spots with the serve. Very complete player.

"First semi-finals for him, so of course he doesn't have much to lose."

- 'Magical experiences' -

Tsitsipas meets Khachanov in the other last-four showdown on Friday, aiming to snap a run of three semi-final losses in Melbourne, including over the past two years.

Now 24, he believes he has matured and that this could finally be his year as he bids to become the youngest champion since Djokovic won the title in 2011 aged 23.

"I'm feeling great with my tennis. I don't think I felt so good in a long time," the Greek said.

"I've said it -- I'm a different player (from the past), playing different. My mentality is different."

He has won all five previous encounters with Khachanov, most recently at the Rome Masters last year, and said he was eager to face the Russian again.

"It's a match that I'm looking forward to," he said. "I'm looking ahead for more, for better. Looking to create some magical experiences here in Australia."

The 26-year-old Russian also made the semi-finals at September's US Open.

He has now made the quarters or better at all four Grand Slams and will draw on the experience when he plays the Greek star.

"I think the first semi-finals, which I did in US Open, that gave me an extra boost and extra confidence to show where I really am, and what I can do when I'm at my best," he said.

"I think all those things together, they push me to where I am right now."