Novak Djokovic survived a huge scare to reach the third round of the Australian Open on Wednesday, beating home favourite Alexei Popyrin to stay on track for a historic 25th Grand Slam title.

The world number one showed his trademark mental strength to face down his inspired opponent, prevailing 6-3, 4-6, 7-6 (7/4), 6-3. Djokovic was kept on court for more than four hours in his first-round victory over teenager Dino Prizmic, admitting he was "a bit under the weather".