Rafa Nadal’s uncle and coach Toni has added his voice to growing criticism of the Madrid Open’s blue clay courts, and hit out at tournament owner Ion Tiriac and the men’s tour organisers the ATP over the switch from the traditional red dirt. World number two Nadal, who was knocked out in the third round by Spanish compatriot Fernando Verdasco on Thursday, and number one Novak Djokovic have complained the blue clay is too slippery and have threatened to boycott the Masters event next year unless the red surface is reinstated. “The fact that the ATP gave permission for this tournament is an outrage,” Toni Nadal told Spanish radio.