Australian Open: Novak Djokovic was made to toil in his fourth round win over Daniil Medvedev. © AFP Drained Novak Djokovic admitted he “didn’t feel so great” after surviving a physical fourth-round examination against 15th seed Daniil Medvedev at the Australian Open. The world number one came through an almost three-and-a-half hour, four-set grind that extended into the early hours of Tuesday morning (local time). Djokovic dropped a set for the second match running but won 6-4, 6-7 (5/7), 6-2, 6-3 at 12:43 am to set up a quarter-final against Japan’s eighth seeded Kei Nishikori on Wednesday. Serb Djokovic and Russian Medvedev both needed attention from the trainer during an exhausting encounter liberally sprinkled with punishing rallies of 30 shots or more.”I didn’t feel so great, you know, in the last 20 minutes of the match,” Djokovic told reporters.”So we’ll see tomorrow how the body reacts, but I’m confident I can recover and I can be ready for next one,” he said.”It was just, you know, a little bit of fatigue, a little bit of back. Nothing major. But there are a couple of things that have surfaced,” said the 14-time Grand Slam champion.”It was kind of a cat-and-a-mouse game…