INDIAN WELLS, Calif. -- Defending champion Juan Martin del Potro has withdrawn from next month's BNP Paribas Open because of a knee injury.
Del Potro said Wednesday through tournament officials that he has been advised to rest by his doctors and he hopes to return to action soon. He defeated Roger Federer to win his first Masters 1000 title last year in the Southern California desert.
The fourth-ranked Argentine lost in the quarterfinals of last week's Delray Beach Open in Florida. It was del Potro's first tournament since injuring his knee at the Shanghai Masters in October.
Del Potro already had pulled out of this week's Mexican Open in Acapulco, which he won last year. He also missed the Australian Open in January.
With del Potro's withdrawal, Taro Daniel of Japan moves into the men's draw.
The women's draw already lost two-time winner Maria Sharapova, who withdrew with a shoulder injury.
The tournament runs March 6-17 in Indian Wells.