Top-ranked Rafael Nadal has withdrawn from the Swiss Indoors next week, denying fans a possible final against Roger Federer.

Nadal says he's taking medical advice to protect ''over stressing of the (right) knee.''

He says the injury affected him last week in Shanghai, where he lost the final to Federer in two sets.

Federer's win over Nadal was a fifth straight against his longtime rival. That streak started in Basel in 2015 when Federer won the final of his hometown tournament.

In Nadal's absence, the No. 2-ranked Federer will be top-seeded as he seeks an eighth Basel title.