Second seed Rafael Nadal reached the Australian Open quarter-finals when Paul-Henri Mathieu retired injured in the second set of their fourth-round match.
The Spaniard was leading 6-4 3-0 when Frenchman Mathieu, who earlier had treatment on a leg injury, was forced to quit.
Nadal will play Finland's Jarkko Nieminen, the 24th seed, in the quarter-finals.