The RM 027 Tourbillon was released in a sold-out limited edition of 50 pieces in 2010 at £424,000 ($670,500).
It is common for tennis stars to have a luxury watch endorsement, with players usually seen wearing them in photographs following a match. However, Nadal's watch is unique, designed to be actually worn during the star's high-intensity games.
To cope with the stress, the watch weighs just 18g and is a mechanical watch, meaning that it requires the movement of the wrist, rather than a battery, for its power supply. This makes it the lightest mechanical watch in the world.
To keep weight to a minimum, Mille has used lightweight materials such as LITAL for the moving components, a carbon-based composite for the casing, and titanium for the baseplate.
As well as superb shock-resistance and performance, the watch also incorporates a tourbillon - a feature rarely seen in sports watches.
"It is an honour that someone like Richard has chosen me as one of his ambassadors. I know that he has worked very hard to be able to create this very special watch. I am sure it will be a special and successful partnership," said Nadal of the watch.
Also starring is a diamond-set Patek Philippe Ref 5073, which will appear at auction for the first time since its release.
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