Japanese No.8 seed Kei Nishikori has come back from two sets down to book a spot in the second round of the Australian Open after his Polish opponent withdrew with severe cramping.

After starting slowly, the super-fit Nishikori bounced back hard and 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 pulled the pin.

The world No.176 was making his grand slam singles debut.

Nishikori, the 2014 US Open finalist, advanced to a second-round showdown against either towering Croatian Ivo Karlovic or another Pole, Hubert Hurkacz.

Nishikori has reached the fourth round or better at the Australian Open in each of the previous six years.

In other men’s action early on day two, 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.

American Ryan Harrison was another straight-sets winner as he eased past Czech Jiri Vesely 6-0 7-5 6-3.