World No.1 Novak Djokovic dispelled any concerns about his health by powering into the second round of the Australian Open on Tuesday as Stan Wawrinka made an equally impressive start to his maiden grand slam title defence.

Djokovic, the four-time Open champ who had been troubled by a virus in the lead-up to the first major of the year, showed no after-effects in a regulation 6-3 6-2 6-4 victory over Slovenian qualifier Aljaz Bedene.

“It hasn’t been an ideal couple of weeks in terms of preparation but I’ve fought my way through,” said Djokovic.

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“Now it’s behind me and I’m only looking forward.

“I did well today in terms of responding to the slow start ad feeling a bit rusty on the court.

“Hopefully the next one will be even better.”

The Serb won six titles in 2014, including the year-end championship in London, but started this campaign this year with a surprise semi-final loss to Ivo Karlovic in Doha.

Wawrinka made a flying start to his title defence, crushing Turkey’s Marsel Ilhan in straight sets.

The Swiss star broke through for his maiden grand slam title last year at Melbourne Park, beating Djokovic in the quarters and Rafael Nadal in the final.

The No.4 seed could hardly have been more impressive on Tuesday, smashing Ilhan 6-1 6-4 6-2 to set up a second-round clash with Romanian qualifier Marius Copil.

“The first match in a grand slam is never easy, but I’m happy with the way I played today,” said Wawrinka.

“It felt great to come back on the court.

“I played some good tennis and I have confidence with my game in general.”

Playing in his first major since the thrilling run to last year’s US Open final, Japanese No.5 seed Kei Nishikori proved too good for Spanish veteran Nicolas Almagro, winning 6-4 7-6 (7-1) 6-2.

He will play Croatian Ivan Dodig in the second round.

Nishikori has advanced at least to the fourth round at each of the previous three Australian Opens and will fancy his chances of again going deep into the first grand slam event of the year.

It was also the first time since 2008 that Almagro had been beaten before the third round at Melbourne Park.

Nishikori was joined in the second round by eighth-seeded Canadian Milos Raonic, who won 7-6 (7-3) 7-6 (7-3) 6-3 against Ukrainian qualifier Illya Marchenko, and No.9 David Ferrer, a semi-finalist at Melbourne Park in 2011 and 2013, beat Brazilian Thomaz Bellucci 6-7 (2-7) 6-2 6-0 6-3.

Italian Fabio Fognini, the No.16 seed, was upset 4-6 6-2 6-3 6-4 by Colombian Alejandro Gonzalez.

-AAP