The Big Three is the year-end top three, something that last happened in 2014.
With Novak Djokovic at No. 1, Rafael Nadal at No. 2 and Roger Federer at No. 3 on Monday, that trio of tennis greats leads the season's final ATP rankings for the seventh time.
This is the first time, though, that each of those three men spent some time at No. 1 during the same year. The seven changes there were the most since 1999, when there were eight.
Djokovic won Wimbledon and the U.S. Open in 2018, while Federer took the Australian Open, and Nadal earned the title at the French Open.
They accounted for Nos. 1-3 in the final rankings in 2007-11 and 2014, too.