Defending champion Novak Djokovic fought off an incredible five-hour challenge from Swiss Stanislas Wawrinka to reach the quarter-finals at the Australian Open early Monday.

The Serb world number one was down a set and 1-4, before recovering to go through in five sets 1-6, 7-5, 6-4, 6-7 (5/7), 12-10 in 5hr 2min on Rod Laver Arena.