By winning his second round-robin match this week at the ATP Finals--combined with Rafael Nadal's dropping a round-robin match to nemesis Robin Soderling--Roger Federer has clinched the #1 ranking in men's tennis for the year. Nadal had a chance to eclipse the Swiss player in this final event of the year, but now will finish as #2. Federer earned this honor with an impressive win over Andy Murray today.