Spanish player Rafael Nadal celebrates after winning the men's singles semi-final tennis match against Spanish player Roberto Bautista Agut at the Madrid Masters at the Magic Box (Caja Magica) sports complex in Madrid on May 10, 2014. Nadal won the match 6-4, 6-3
Petra Kvitova of Czech Republic in action against Svetlana Kuznetsova of Russia in the final during day eight of the Mutua Madrid Open tennis tournament at the Caja Magica on May 9, 2015 in Madrid, Spain
Swiss Davis Cup team player Roger Federer speaks during a press conference on November 18, 2014 in Villeneuve-d'Ascq, northern France, prior to the Davis Cup tennis tournament final against France on November 21-23, 2014. Switzerland's hopes of a first ever Davis Cup win lay in the balance as the team awaited word on just how badly Roger Federer had injured his back ahead of this week's final against France in Lille
Angelique Kerber has lost an average of 5 games per match.