BNP Paribas Open in Indian Wells will test Nadal's knee

Rafael Nadal is not sure how his injured left knee will respond to his first hardcourt match of the year at the BNP Paribas Open.

Nadal is a two-time champion and three-time finalist at this event. He has not played a match on a hard court in almost a year and is only a month into his comeback from a left knee injury that sidelined him for seven months.

He has played three tournaments since returning, all on clay, and won titles in Brazil and Acapulco, Mexico, after losing to Horacio Zeballos in the final in Chile in his first week back.