Roger Federer wants more drug testing in tennis . Due to the debate over Viktor Troicki 's eligibility . Federer defeated Richard Gasquet at ATP World Tour Finals . Novak Djokovic into retirement after beating Juan Martin Del Potro .
Roger Federer wants more drugs testing in tennis . Reacting to the debate over Viktor Troicki 's punishment . Federer beats Richard Gasquet at ATP World Tour Finals . Novak Djokovic into semifinals after beating Juan Martin Del Potro .