A delighted Roger Federer said he exceeded his own expectations when thrashing Tomas Berdych to reach round four of the Australian Open on Friday.

Federer delivered a masterclass on Rod Laver Arena, dropping just 14 points on serve in a 6-2 6-4 6-4 demolition of Berdych.

After producing comfortably his best display since returning from a six-month injury lay-off, to enhance his credentials as a potential winner at Melbourne Park, Federer was understandably positive in an on-court interview with former world number one Jim Courier.

"I always felt that probably against better-ranked players you always lift your game naturally, because you have to," said the Swiss. "I know Tomas really well, so I think usually we feed off each other. He didn't, I did ... I couldn't be happier right now.

"I had no expectations really. I felt as though I struggled in the early rounds here the last few days, but today was different [and] I served great. It's been unbelievable and I did surprise myself."

Having knocked out the 10th seed, Federer faces world number five Kei Nishikori in the last 16 and is relishing the challenge.

"I guess I'm ready now," he added. "I like Kei, I've always been a fan of his game. He's got maybe the best backhand in the business right now, so I've got my work cut out, but I hope I can play a good match."

Federer's interview ended on an amusing note as he was asked about eating ice cream on the evening before facing Berdych.

"I like my ice cream and I like my chocolate. That's my diet. This is an everyday thing - I like my treats, absolutely," said the 35-year-old with a smile.

"I don't even feel bad about it. I feel good that I can do it and play tennis at the same time."