Roger Federer beats Kei Nishikori to reach Australian Open quarter-finals

Roger Federer continued his remarkable return from injury by seeing off Kei Nishikori in five sets to reach his 13th Australian Open quarter-final.

The 35-year-old beat fifth seed Nishikori 6-7 (4-7) 6-4 6-1 4-6 6-3 to keep alive his hopes of an 18th Grand Slam and fifth Australian Open title.