. . . . . "Hard" . . . . . . "The 2015 US Open was a tennis tournament played on outdoor hard courts. It was the 135th edition of the US Open, the fourth and final Grand Slam event of the year. It took place at the USTA Billie Jean King National Tennis Center.Marin \u010Cili\u0107 was the defending champion in the men's singles event, but lost to eventual champion Novak Djokovic in the semifinals."@en . . . "4.22534E7"^^ . . .