Djokovic quells Alcaraz challenge to reach Australian Open semis

Novak Djokovic beat young rival Carlos Alcaraz 4-6 6-4 6-3 6-4 in a battle worthy of a title clash to charge into the Australian Open semi-finals on Tuesday and remain in the hunt for a record 25th Grand Slam title.

In the latest chapter of a generational rivalry that has played out on the biggest stages, including last year's Olympic final in Paris which Djokovic won, it was the 37-year-old who maintained his hardcourt dominance over Alcaraz.

Defeat was a blow for the 21-year-old Spaniard as the French Open and Wimbledon champion's bid to become the youngest man to complete a career Grand Slam went up in flames, and he was left to digest his third loss to Djokovic on the surface.

"I wish this match today was the final," said Djokovic, who next takes on German second seed Alexander Zverev in what would be a men's record 50th major singles semi-final for the Serb.

"It's just one of the most epic matches that I've played on this court, on any court, really. So thank you all for staying at 1:00 am to watch us and support the players."

Some loose shots at the start of the match put Alcaraz on the back foot but he fired a magnificent backhand winner to pull back a break and was rock solid from there, vaulting to a 5-4 lead in a physical opening set after Djokovic made an error.

Having dropped his serve for a second time, Djokovic took an off-court medical timeout and returned with his left thigh taped up, but the seventh-seeded Serb could not prevent Alcaraz from holding to love with a big ace at the end to clinch the set.

"Since I'm still in the tournament, I don't want to reveal too much, obviously," Djokovic said.

"The medication started to kick in, and they helped. No doubt, I had to take another dose. I mean, this sounds awful. Me taking another dose. If I lost that second set, I don't know if I would continue playing, but I felt better and better."