Rafael Nadal's bid to win four consecutive Grand Slam tournaments appears in jeopardy early in his quarterfinal match at the Australian Open.

Nadal took a medical timeout after three games against fellow Spaniard David Ferrer on Wednesday, apparently for an upper left leg or back problem. He lost the first set 6-4.

Last year — also on the Australia Day holiday — he retired from his Australian Open quarterfinal against Andy Murray due to a right knee injury.

That injury took him off the tour until March, but he recovered to win last year's French Open, Wimbledon and U.S. Open titles. He's trying to add the Australian Open to be the first man since Rod Laver in 1969 to hold all four majors at once.