Roger Federer is a Swiss professional tennis player who is currently ranked world No. 2 in men's singles tennis by the Association of Tennis Professionals (ATP). Federer has won 20 Grand Slam singles titles—the most in history for a male player—and has held the world No. 1 spot in the ATP rankings for a record total of 310 weeks, including a record 237 consecutive weeks. After turning professional in 1998, he was continuously ranked in the top ten from October 2002 to November 2016. He re-entered the top ten following his victory at the 2017 Australian Open. Federer is widely considered to be one of the greatest players of all-time.