Roger Federer today became the first man in history to win 300 Grand Slam matches as the Swiss beat Grigor Dimitrov to reach the Australian Open fourth round.

Dimitrov was once dubbed Federer's apprentice for his talent and elegant style of play.

But it was the 34-year-old who proved himself the master on Rod Laver Arena, winning 6-4 3-6 6-1 6-4.

Federer was far from his free-flowing best and even looked flustered when Dimitrov clinched the second set but an early break in the third quickly turned the tide.

It was one-way traffic thereafter as Federer sealed victory in two hours and 40 minutes to set up a fourth-round meeting with Belgium's David Goffin.

"Today didn't come automatically, I had to push myself, remind myself what to do," Federer said.

"These are the great matches to win, I tell you that, because you're not going to feel 100 per cent great every single time when you go out there.

"But it's important to win those matches maybe where you felt a little off almost sometimes."

Federer and Dimitrov are good friends off the court and a video quickly circulated on the internet of the pair before the match, relaxing together as they waited to go on.

They were watching Maria Sharapova playing American Lauren Davis and one rally particularly excited Federer, who yelled and leapt out of his seat.

"We know each other quite well and we were pretty chilled going into the match," Federer said.

"Sometimes you don't look much at the other guy but with Grigor it's different, like with other guys on tour. There are many guys I would speak to before a match. That was the situation today.

"I'm happy it still exists. We're not that far down the road where it's so professional where you can't even look at the guy before you walk on court."

Federer's 300 Grand Slam wins include 17 major successes, while he has reached 27 finals and 38 semi-finals. This year's Australian Open is his 65th consecutive appearance at a major tournament.

"It's very exciting, I must tell you," Federer said.

"Like when I reached 1,000 career wins last year, it was a big deal for me. It's not something I ever aimed for or looked for, but when it happens, it's very special.

"You look deeper into it, I guess, where it's all happened and how, so it's very nice. I'm very happy."