World number 1 and defending Australian Open champion Novak Djokovic needed five sets to beat 14th seed Gilles Simon in the fourth round of the Aussie Open on Sunday. The world No. 1 closed out the Frenchman 6-3, 6-7 (1), 6-4, 4-6, 6-3 in a draining 4 hours, 32 minutes to reach the quarterfinals. Djokovic committed an unprecedented 100 unforced errors, as Simon steadily wore him down. The Djoker faces Kei Nishikori, who easily dispatched Jo-Wilfred Tsonga in straight sets. The winner of that match will likely play Roger Federer in the semis.