The defending champion Novak Djokovic and Andy Murray have reached the semi-finals at the Australian Tennis Open so the big four of the mens game are the last four in Melbourne.
Djokovic overcame a leg strain and breathing difficulties to grind down the Spaniard David Ferrer 6-4 7-6 6-1.
The world number one struggled briefly with a hamstring twinge and said he felt short of oxygen throughout the match, but he said he'd be fully fit for tomorrow's semi-final against Andy Murray who brushed aside a tired looking Kei Nishikori in straight sets.
Maria Sharapova and Petra Kvitova will meet in the womens semi-finals after straight sets quarter-final wins over unseeded opponents Ekaterina Makarova and Sara Errani.
