Tennis ace Novak Djokovic has been given a special golden racket weighing a whopping 17.6 lbs and made using 24-karat gold. The Serbian tennis player, who recently won his 23rd Grand Slam, the only person to do so, was surprised by the gesture after receiving the unique gift from the American-Austrian manufacturer of sports equipment Head. The company, which sponsors Djokovic, gave him the golden tennis racket, which reportedly weighs…