Novak Djokovic returned to No. 1 on Monday (Nov 5) after a two-year absence and is assured of becoming the first man in the history of the ATP rankings to finish a season at the top spot after being outside the top 20 during that season.
That's because the man he overtook, Rafael Nadal, is done for 2018.
Nadal withdrew from the ATP Finals on Monday, citing an abdominal injury, and announced he was having arthroscopic surgery on his right ankle.
Djokovic will be the ATP's year-ending No. 1 for the fifth time, pulling even with Roger Federer and Jimmy Connors for the second most since the computer rankings began in 1973. Pete Sampras holds the record of six.