Djokovic, who is looking for an 11th title at Melbourne Park, showed all his battling qualities in an intense quarter-final win over Carlos Alcaraz (21) and the veteran faces another huge task to overcome second seed Zverev.
World number one Jannik Sinner (23) will also be in action when he continues his title defence against American 21st seed Ben Shelton (22) in the night session on Rod Laver Arena.
Djokovic braced for Zverev challenge
Djokovic and Zverev have met 12 times before, with the Serb winning on eight occasions including their latest encounter at the 2023 Cincinnati Open.
Zverev, who struggled to hit top form during two seasons disrupted by serious injury, looked back to his best last year, winning the Masters 1000 titles in Rome and Paris as well as finishing runner-up at the French Open.
The German knocked out American 12th seed Tommy Paul in the last round to reach a third Australian Open semi-final and he believes he has what it takes to get the better of Djokovic.
"I'm going to prepare myself for a very intense and high-level match," Zverev told reporters.
"I know I have the level. Hopefully, I can do that again (beat him)."
At 27, the second seed is still seeking his first Grand Slam title and hopes to become the first German man to win the Australian Open since Boris Becker in 1996.
Djokovic, the last member of the 'Big Three' still standing following the retirements of Roger Federer and Rafa Nadal, appeared hampered by an injury early in his thrilling win over Alcaraz but hopes to be fighting fit to face Zverev.
"It is definitely going to be challenging from every aspect I mean, I am playing Zverev, who is in great form, and he is going for his first Grand Slam," Djokovic said.
"I think he loves the conditions. He's got a big serve. He's a super dangerous opponent on this surface against anyone. The extra day with no match comes at a good time.
"I will try to do as much as I possibly can with my recovery team...
"But if I manage somehow to... be physically good enough, I think mentally, emotionally, I'm as motivated as I can be."
Sinner seeking to maintain edge over Shelton
Sinner easily dispensed with home favourite and eighth seed Alex de Minaur in the quarter-finals and looks to have shrugged off the medical issue that left him dizzy and shaking against Holger Rune in the last 16.
While Sinner is into his fifth Grand Slam semi-final, Shelton, who turned pro in 2022, is set to play just his second after reaching the last four at the 2023 US Open.
Sinner holds a 4-1 head-to-head record against Shelton but the 23-year-old Italian remains cautious ahead of their clash.
"One of the biggest serves we have on tour," Sinner said.
"He's a very aggressive player, an all-around player. He can go to the net. He can stay back.
"It's a difficult match for both of us. We know each other a little bit better now. We had some tough matches in the last year, so let's see what's coming."
Order of play on Friday:
Mixed doubles final:
Kimberly Birrell/John-Patrick Smith vs Olivia Gadecki/John Peers - 02:00 CET
Men's singles semi-finals:
