World No. 1 Novak Djokovic says it's doubtful that he'll play Olympic mixed doubles with either Ana Ivanovic or Jelena Jankovic. "Most likely I will not play mixed doubles in London, because I already have singles and doubles. I think it will be too much," the Serbian said. "I'll decide a bit later. I support it. Why not have mixed doubles as a discipline in tennis in the Olympic Games?"