'A champion's champion': Nadal and other tennis stars react to Roger Federer retirement

Swiss star announces retirement from tennis after stellar careerIn pictures: Federer’s remarkable tennis careerThe tributes poured in quickly on Thursday when Roger Federer announced his retirement from tennis after a career than lasted more than two decades and brought him 103 singles titles.Federer’s rivalry with Rafael Nadal has been a defining part of tennis this century, and the S