Novak Djokovic knows he cannot afford another match littered with mistakes when he faces No.7 seed Kei Nishikori in Tuesday's Australian Open quarter-finals. The top seed squeezed past Frenchman Gilles Simon in five sets in just over 4\xC2&#189; hours in the fourth round despite racking up a remarkable 100 unforced errors.  
Djokovic (left) admitted he was well below his best but will not dwell on the sub-par display. "In terms of a level that I've played, it's the match to forget for me," Djokovic said. "I won it, so it's pretty good. When you're playing that bad and still manage to win - hopefully it's going to be better the next one." Nishikori advanced with much less fuss, dispatching No.9 seed Jo-Wilfried Tsonga in straight sets. "It was one of the best matches I had this week," Nishikori said. "I played good tennis, through three sets - all three sets." Japan's top-ranked player trails Djokovic 5-2 in their head-to-head battle, with Nishikori last beating the Serb in a semi-final boilover at the US Open in 2014. He planned to watch a replay of that match before he takes the court on Tuesday. "I'm ready to beat him again," Nishikori said.