(Reuters) - One of the great sporting rivalries will be renewed at Indian Wells on Saturday when Roger Federer and Rafa Nadal clash in a semi-final at the BNP Paribas Open, providing the Spaniard's troublesome right knee does not keep him off court.

The multiple Grand Slam champions both won their quarter-finals on Friday, although Nadal in particular had to work hard to overcome Russian Karen Khachanov 7-6(2) 7-6(2) in a match during which he required treatment on the knee.