So while Hewitt ended his career with a second-round loss to Spaniard David Ferrer at Melbourne Park, Federer is still going strong, into the semi-finals of the Australian Open for the 12th time where he will come up against world No. 1 Novak Djokovic tonight.

Defending champion Djokovic recovered strongly from his five-set struggle against Gilles Simon as he ousted Nishikori 6-3, 6-2, 6-4, after Federer swept aside Berdych 7-6 (7/4), 6-2, 6-4.

The result means Djokovic now leads the pair's head-to-head for the first time 23-22, and he goes through to meet either Britain's Andy Murray or Canadian Milos Raonic in Sunday's final.

Closing out the match when Federer netted a backhand, Djokovic was left celebrating another memorable victory as he stood one win away from a record sixth title at Melbourne Park.

Novak Djokovic of Serbia celebrates after defeating Kei Nishikori of Japan in their quarterfinal match at the Australian Open tennis championships in Melbourne, Australia, Tuesday, Jan. 26, 2016.

Djokovic is seeking his 11th Grand Slam title while Federer, 34, is looking to extend his record tally to 18 - and both will want to take charge of their head-to-head, which is locked at 22-22.

Djokovic, who won three of four Grand Slams in 2015, held serve throughout the fourth, broke Federer late and closed out the match.

Considering he has had the upper hand in best-of-five matches against Federer recently, many predict yet another Djokovic victory today. He was on a different planet against Federer, needing just 54 minutes to lock in the first two sets.

"In the end of the day you are battling yourself the most", Djokovic said of his turnaround.

Striving to become the oldest Open champion since Ken Rosewall in 1972, Federer had Djokovic down 0-30 immediately upon the resumption of play after the roof was shut.

Asked after she beat Johanna Konta in the semifinals if she would seek out Graf's advice, Kerber laughed and said, "Steffi, write me please".

Two things can be said at the moment, about Thursday's epic semi-final clash.

Then the rain came, probably at the wrong time for Federer.

There appeared no way back after Djokovic broke the third seed twice more and barely dropped a point on his own serve in storming to a two-set advantage inside an hour. But the Serb won the two most important: the Wimbledon and U.S. Open finals, both played in the best-of-five format.

He saved a break point at 2-2 and broke on his fourth chance in the sixth game.

Having never beaten Djokovic after losing the opening set, the signs were ominous for the Swiss. "If she wins, I'll be very happy for her. I'm sure she'll feel the same way", Williams said. He looked vulnerable and Federer knows he will need to play his best to top his foe. Ball boys and girls used towels to dry up a few water spots, and play resumed to allow Kerber to serve and take the set. After four minutes, Federer was two games down.