German superstar Alexander Zverev and Japanese ace Kei Nishikori have led the big names safely through to the second round on day two of the Australian Open in Melbourne.

Fourth-seeded Zverev easily accounted for Slovenia’s Aljaz Bedene 6-4 6-1 6-4 in his first outing since pulling out of an exhibition in Adelaide last week with a hamstring strain.

He was also hindered in practice with an ankle issue but wasn’t bothered on Tuesday in his straight-sets workout.

“I had about 86 injuries coming into this tournament,” Zverev said.

“My ankle is still a little bit sore, a little bit swollen. But everything is going to get better, hopefully a bit every day.”

Yet to make a grand slam semi-final, the 21-year-old is hoping break through after taking down Roger Federer and Novak Djokovic in successive matches to claim the 2018 season-ending tour championship in London.

“It was an unbelievably special moment. I was very proud of that moment,” he said.

“(I) try to take that into the grand slams and enjoy playing the best players. That was maybe the most-important thing about winning that tournament.”

“I’ve done everything I can in the preparation. Now it’s either I play well or I don’t. You have to enjoy it as much as you can and the results come.”

Nishikori earlier recovered from two sets down to book a spot in the second round when his Polish opponent withdrew with cramping.

Nishikori was leading 3-6 6-7 (6-8) 6-0 6-2 3-0 when wilting qualifier Kamil Majchrzak informed the chair umpire he was unable to continue.

The pair had been on court for two hours and 48 minutes on another hot day in Melbourne when Majchrzak, a grand slam rookie, pulled the pin.

Nishikori, the 2014 US Open finalist, will next play towering Croatian Ivo Karlovic, a 6-7 (5-7) 7-6 (7-5) 7-6 (7-3) 7-6 (7-5) winner over Pole Hubert Hurkacz.

In other men’s action, Russian No.15 seed Daniil Medvedev – who lost the Brisbane International final to Nishikori earlier this month – thumped South African qualifier Lloyd Harris 6-1 6-2 6-1.

Medvedev will play Ryan Harrison for a spot in the third round after the American eased past Czech Jiri Vesely 6-0 7-5 6-3.

Croatian 11th seed Borna Coric breezed past Belgian Steve Darcis 6-1 6-4 6-4 to seal a date with Hungarian Marton Fucsovics.

Italian 12th seed Fabio Fognini progressed when Spaniard Jaume Munar quit while trailing 7-6 (7-3) 7-6 (9-7) 3-1.

Fognini faces unseeded Argentine Leonardo Mayer next.