The great charity auction for the 20th anniversary of the Mutua Madrid Open opened this Friday, April 1 at 12:00 a.m., giving all fans and collectors the opportunity to bid on a large collection of objects that are part of the history of tennis.In close collaboration with Durán Arte y Subastas, the charity auction will be published online from April 1 and will be held on the 20th of the same month with a face-to-face event, which will take place at Durán Arte y Subastas (Calle Goya, 19 -1º) where All lots will be exposed from April 1.The shoes with which Rafael Nadal played at this year’s Australian Open, the rackets of Roger Federer, Garbiñe Muguruza, Novak Djokovic or Maria Sharapova, the clothes of David Ferrer, the title of …