Dominant Novak Djokovic marches past Fernando Verdasco

The Serbian cemented his status as tournament favourite with a forensic dismantling of the number 31 seed Verdasco, who barely laid a racket on the Djokovic serve.

Verdasco matched Djokovic in the first set, but after the first-set tie-break, when he missed six break points, the world number one upped his game and powered through.

He broke Verdasco early in the second set, and then used his crashing serve to secure three consecutive aces and save a trio of break points.

So rarely was the end result in doubt that the greatest moment of tension came when a fan chose to propose to his girlfriend during a change of ends. She said yes; Djokovic applauded.

In festive mood after the match's conclusion, Djokovic gave his towel and sweatbands to a fan who was almost overcome with the excitement of it all.

And then he promptly persuaded the spectators in the Rod Laver Arena to sing 'Happy Birthday' to his mother along with him.

The four-times winner in Melbourne will face Gilles Muller of Luxembourg in the last 16, after Muller defeated John Isner in straight sets.

Djokovic said he had never played Muller before but had already accumulated quite a dossier of intelligence on the left-hander.

"He's been on the tour for many years. Best junior in the world. He's got a great serve, lefty," Djokovic said when asked about what he knew about the 31-year-old. "He comes to the net. He has a nice slice serve. That's his favourite. He struggled a little bit with injuries last couple years, but I think last six months has been playing some of his best tennis."

The level of discussion of his next opponent surprised many, who are used to players blandly stating they have not even looked at the draw let alone studied potential opponents.

"It's my job to know my colleagues, tennis players, especially if I get to play them," Djokovic said. "So I do my homework. To come to the court and play the way I want to play against somebody I never played against before...can be dangerous because of the uncertainty of what he's going to do in some moments. That's why I've got to do my homework, sit down with the team, prepare myself well with the video analysis."

Djokovic had no such concerns with analysing Verdasco and was well aware of the threat the former top-10 player posed. The Spaniard had taken Rafa Nadal deep into the night in a five-hour, five set marathon during the 2009 semi-finals in Melbourne and only trailed the Serb 6-4 in their career head-to-head record.

"It was a big challenge for both of us," Djokovic added. "He was a former top-10 player. Somebody that loves playing on the big stage, a powerful game. (The) turning point probably was winning the tiebreaker as close as it was ... so I'm glad to go through in straight sets."