From one GOAT to another on Rod Laver Arena. Serena Williams departs and Roger Federer comes out to face Filip Krajinovic. John Millman awaits the winner in the third round.

A double fault from Krajinovic delivers three match points. Federer sends the first long on the backhand wing, the Serb crunches down an unreturnable serve for the second before the six-time champion wraps up the win with a forehand. Supreme form for Federer, despite a minor blip in the second set. John Millman is next up as he looks to avenge his 2018 US Open loss to the Aussie.

Another routine hold to Federer, this time to 15. Sealed with an ace and this contest has gone very flat after livening up in the second set.

Despite treatment on his right arm, Krajinovic is engaging in rallies just fine, he's being bettered by Federer, who gets his second break, this time to 15. Curtain call now...

Whether or not Krajinovic is fit to continue or not, it is hard to say. That's because some supreme serving from Federer meant he barely got a racquet on the ball.

While we wait for Krajinovic to receive treatment (on what appears to be his arm), enjoy...

Krajinovic battles to get himself to 40-30 on his own serve but is beaten by a lovely Federer lob, despite his attempted tweener. A long rally follows, with Federer bringing up break point as the the Serb nets. He gets himself out of trouble, though, and hangs in there to hold a long, long game. But he's called for medical assistance...

Federer is hitting all the lines again. There are two challenges in this service hold to 15 and both found Federer hitting the very edge of the line. What can anyone be expected to do against that?

The third set starts in much the same manner as the second, with Federer getting the early break. How much fight does Krajinovic have left in him?

And that's two sets to love. Federer in complete control now, just as Krajinovic had worked his way back into the match. So disappointing for him.

Just as Krajinovic battled into this set, Federer restores his break. The critical point was at 0-15, when Krajinovic blasted a routine overhead well wide, with Federer lobbing the ball high desperately to stay in the point. When Krajinovic nets a backhand volley, the Swiss has his lead again.

For the second straight game, Krajinovic gets a break point chance but this time Federer comes to net to save it after a decent serve out wide. A second break point follows as Federer nets and he gets it! The Swiss' backhand is long and we're back on serve in the second set.

Krajinovic has a foothold in this match now. Federer looks to break him after getting to 15-30 with a deft drop shot but Krajinovic hits a fine winner and reverts to serve-volley to get out of trouble.

When your luck's out... Krajinovic goes 0-15 up on the Federer serve and is well in the rally on the second point but Federer gets the dead net cord. Krajinovic comes back from 40-30 down though and gets to break point but the opportunity soon vanishes and the Swiss holds.

Watch and admire...

Federer has done a good job of getting in Krajinovic's head here as the Serb comes to net and is beaten by a forehand pass. He then stays back and is beaten by a Federer backhand, then comes to net and is beaten by an extraordinary crosscourt forehand winner on the run. Federer squanders both break points, though and he holds!

Krajinovic is doing better at engaging Federer in rallies. He starts with a missed opportunity on the backhand from a tight angle but gets a point with a good pass. Nothing he can do to stop Federer from holding to 15 though.

A welcome love hold for Krajinovic to stem the flow coming from the other side of the court. It's been one-way traffic so far but Krajinovic has been impressive at the net, to be fair to him.

We're running out of ways to describe this Federer performance. He fires down another ace onto the back edge of the service line to hold and there's only one person in this contest.

New set, same Federer. He races to 0-30 in no time, gets pegged back but still gets his break.