MELBOURNE, Australia– Novak Djokovic was wondering, right along with everyone else, what sort of shape Roger Federer would be in for their Australian Open semifinal.

At age 38, despite dealing with a painful groin muscle and coming off a draining five-setter, Federer came out just fine, it seemed, and soon was up 4-1 and love-40, holding a trio of break chances as Djokovic served.

Didn't last. Federer couldn't sustain that level. Neither his body nor Djokovic would let him.

Casting aside a bit of a poor start, Djokovic stretched his Grand Slam winning streak against Federer to six in a row with a 7-6 (1), 6-4, 6-3 victory Thursday night that earned the defending champion a record eighth trip to the final at Melbourne Park.

The No. 2-seeded Djokovic will try to collect a record-extending eighth Australian Open title Sunday against No. 5 Dominic Thiem or No. 7 Alexander Zverev.

"Today was horrible, to go through what I did. Nice entrance. Nice sendoff. And in between, it's one to forget, because you know you have a 3% chance to win," Federer said, adding that he discussed beforehand with his team how bad things would need to get for him to stop playing. "Once you can see it coming, that it's not going to work anymore, it's tough."

Djokovic now leads their head-to-head series 27-23, including 11-6 at majors.

"I just want to say, respect to Roger for coming out tonight. He was obviously hurt," Djokovic said. "Wasn't at his best."

ASSOCIATED PRESS