MELBOURNE, Australia -- World No. 1 Rafael Nadal will return to the practice court in two weeks following an injury that forced him to retire from his Australian Open quarterfinal match Tuesday night.

Nadal underwent an MRI on Wednesday in Melbourne, which revealed a Grade 1 injury to his iliopsoas -- or inner hip muscles -- near his right leg. He will take some time off from tennis and focus on physiotherapy.

On Tuesday, after nearly four hours on the court against Marin Cilic, Nadal retired down 2-0 in the fifth set. Noticeably ailing, he walked over to the chair umpire, shook his hand and left the court.

Afterward, Nadal was visibly upset that he couldn't compete at the level he wanted to, but he wasn't sure of the extent of the injury.

His plan is to return to competitive tennis on Feb. 26 in Acapulco, Mexico. Nadal is also scheduled to play Indian Wells and Miami in March.

A year ago, Nadal reached the Australian Open final before falling to Roger Federer in five sets.