PARIS (AP)—Rafael Nadal will have no excuse now if opponents give him a hard time about taking too long between points.

The four-time French Open champion will play matches wearing a Richard Mille watch designed specifically for Nadal, with materials used in space exploration. Mille says Thursday there are 50 for sale—at a price of about $425,000.

Nadal never before has worn a watch while competing.

He flew from Spain to France on Thursday, and was planning to practice at Roland Garros. The tournament begins Sunday.

His uncle and coach, Toni, says Nadal couldn’t flex his knees last year, when his 31-match winning streak at the French Open ended. This year, Toni says, his nephew’s knees are “perfect.”