Nadal moved into a second-place tie with Federer, Djokovic and Jimmy Connors with his fifth finish atop the rankings. Only Pete Sampras has more, with six.
This season, Nadal split the four major titles with Djokovic, winning a record-extending 12th Roland Garros, and 19th major overall at the US Open. He also finished runner-up to the Serbian at the Australian Open, reached the semifinals at Wimbledon (l. to Federer) and added two ATP Masters 1000 crowns in Rome and Montreal.
The Spaniard is bidding to triumph at the season finale in London for the first time, but will need to win Friday against Stefanos Tsitsipas to have a shot of advancing out of his group.