Kei Nishikori has revealed that he had been prepared to go the distance in order to defeat David Ferrer in the Australian Open fourth round.

Last year's US Open runner-up won through in straight sets against the Spaniard, who may have been hampered by a blister to his foot, and the Japanese has admitted that he was surprised to only require just over two hours to reach the last eight.

The 25-year-old said: "I'm always prepared to play five sets against David because was always play long games so I'm surprised to win in three sets.

"I've been playing really well. I've had three good matches before this one so I was confident when hitting through the ball. I'm really happy to win today."

Nishikori will now play defending champion Stanislas Wawrinka, who came through in four closely-fought sets against Guillermo Garcia-Lopez.