Nadal hurt his knee during a victory over Karen Khachanov in the BNP Paribas Open quartefinals on Friday.
Rafael Nadal withdrew from the BNP Paribas Open on Saturday due to knee pain, the tournament confirmed. Nadal was slated to face Roger Federer in the tournament semifinal on Saturday evening in Indian Wells, Calif.
“I warmed up today and I felt that my knee was not good to compete at the level I needed to compete in semifinals," Nadal said in a statement. "It’s tough for me to accept all these things that I’m going through in my career. Sometimes I feel sad because I’m in a disadvantage to all my opponents."
"[I need to] be positive and grateful for all the things tennis has given to me. I feel fortunate for all the things I’ve done in my life and the world of tennis."
Nadal struggled with his knee throughout Friday's quarterfinal match against Karen Khachanov. Nadal required on-court treatment in the second set before a 7-6 (2), 7-6 (2) victory.
Nadal and Federer were slated to meet for the 39th time on Saturday. Nadal leads the all-time series 23–15. He has won nine of 12 Grand Slam battles against Federer.
Nadal last faced Federer in the 2017 Shanghai Masters. Federer won in straight sets, marking his fifth-straight victory in the rivalry. Nadal has not defeated Federer since 2014.