Stefanos Tsitsipas won an Australian Open semi-final on his fourth attempt on Friday, battling into the decider at Melbourne Park with a gritty victory over Russian 18th seed Karen Khachanov.

The Greek third seed triumphed 7-6 (7/2), 6-4, 6-7 (6/8), 6-3 under hot sun on Rod Laver Arena to set up a final against either nine-time champion Novak Djokovic or American Tommy Paul.

At 24, he is the youngest man to reach the final since a 23-year-old Djokovic in 2011.

If either he or the Serbian great lift the trophy, they will become world number one.

"I dreamed as a kid to maybe one day get to play in this court against the best players in the world," said Tsitsipas, who is now 10-0 for the season and on the brink of a first Grand Slam crown.

"So I'm happy with the fight I put out there today. I feel blessed, blessed that I'm able to play tennis at this level. I've been wanting for many years now to put Greek tennis on the map.

"I'm extremely happy that I'm in the final now and let's see what happens," he added.

Tsitsipas has thrived in Melbourne throughout his career after bursting on the scene at the 2019 event as a 20-year-old when he dethroned defending champion Roger Federer in the last 16. (AFP)