Kei Nishikori knows he has a fight on his hands if he's going to stop Roger Federer, after the Swiss rolled back the years with a sensational performance at the Australian Open.

Nishikori only needed to watch a few points of Federer's 6-2, 6-4, 6-4 destruction of Tomas Berdych to realise that the Grand Slam titles record-holder is back with a vengeance.

"For sure it's not going to be easy. He was playing great tennis today. I watched only few points," said the Japanese fifth seed, after beating Lukas Lacko to reach the last 16 and a date with the Swiss great.

"But it's always great to play Roger. It's big challenge for me. I'm just happy to play him because I think we needed him on the tour. Happy to see him back a hundred percent."

Federer made light of his first test since returning from a long injury break, facing zero break points against Berdych on Friday evening and winning 95 percent of points on his first serve.

The 35-year-old hit an equal number of winners off his forehand and backhand, won 20 out of 23 points when he came to the net and was well on top in the rallying statistics.

It was a vintage performance that left Berdych shaking his head as he departed Rod Laver Arena. But Federer won't have it so easy against the hard-running Nishikori on Sunday.

Nishikori, in his prime at 27 and gunning for his first major title, has won two of his six matches against Federer and has started the year well, reaching the Sydney final.

After coming through a five-setter against Andrey Kuznetsov in round one, he was able to recover when Jeremy Chardy retired after just four games of their second-round match.

On Friday he had little trouble against Slovakian qualifier Lacko, breezing through in two hours, 11 minutes with a third straight Melbourne quarter-final now only a match away.

Seventeenth seed Federer, when asked if Nishikori was the favourite due to his higher ranking, smiled: "Yeah, sure, he's the favourite. Maybe.

"I don't know. It doesn't matter. I still have to play Kei. If he's the favourite, I'm the favourite, I don't know. But he's definitely played better and more tennis in recent months.

"But then again, it's a new season. We'll see what happens. But I'm a big fan of his game. He's got one of the best backhands out there. 

"I love how he can crush it down the line or crosscourt. He's got wonderful second serve returns. He's fast on his legs. Strong in his mind. I know how tough he is as the match goes along. He finds his range and his rhythm, he's tough to stop."

Source: AFP