Melbourne:Defending champion Rafael Nadal is out of the Australian Open after retiring with an injured knee during his quarter-final against Andy Murray.
No. 5-seeded Murray became the first British man in 25 years to reach the semi-finals in Australia. Murray was leading No. 2-ranked Nadal 6-3, 7-6 (2), 3-0 on Tuesday night when the Spaniard said he could not continue.