Novak Djokovic is a tennis player.
The ATP Rankings are the Association of Tennis Professionals ' ( ATP ) merit-based method for determining the rankings in men 's tennis . Novak Djokovic . He is considered one of the greatest tennis players of all time . Djokovic has won 12 Grand Slam singles titles , the fourth most in history , and held the No. 1 spot in the ATP rankings for a total of 223 weeks .