Recent doping controversies involving top players have not damaged tennis's reputation but having a single commissioner for the sport would go a long way towards clearing up any confusion surrounding cases, John McEnroe said. Men's world number one Jannik Sinner failed two drug tests in March for trace amounts of the anabolic androgenic steroid clostebol but was cleared of any wrongdoing by an independent tribunal that accepted his explanation of unintentional contamination. Women's world