Greek Tsitsipas had earlier on Saturday upset second seed Jannik Sinner 6-4 3-6 6-4, handing the Italian only his second defeat of the year in the first semi-final.

Norwegian Ruud, who had lost to Djokovic in all five of their previous matches, broke twice early in the first set before the Serbian record 24-times grand slam champion fought back strongly in the second.

But eighth seed Ruud held his nerve as five unforced errors from Djokovic allowed him to go 3-0 up in the decider, and he calmly closed out the victory.

"This is a day I will remember for a long time. Beating a world number one is something I have never done," Ruud said in a post-match interview.

"You know how good these guys are under pressure ... he saved so many break points. I was praying, please, let it be a double fault or something. And maybe someone was listening."

Djokovic, who had beaten Australia's No.1 Alex de Minaur in the quarter-finals, still hasn't won a title this year, and remains on 98 in his glittering career.

The Australian Open champion Sinner made a comeback in the second set after losing the first to Tsitsipas and led 4-3 in the decider when leg cramps forced him to take a medical timeout.

The 22-year-old Italian continued but proved no match for Tsitsipas who won the next three games to clinch victory.

"It was tennis at the highest level that I have been able to play," Tsitsipas said after handing Sinner only his second loss in 27 matches this season.

"He is one of the toughest opponents I have faced so far. To find a way when there were not many, I am extremely proud of that."

The win over Sinner brought Tsitsipas back into the top 10 of the world rankings after dropping out for the first time since 2019 earlier this year.

Australian Associated Press