Paris - Rafael Nadal was confirmed as the year-end world No 1 for the fifth time after the ATP released its season-closing rankings on Monday.
The Spaniard did not make it beyond the group stage of last week's ATP Finals in London but Novak Djokovic's failure to reach the semi-finals meant Nadal closed the year with 9 985 points, 840 clear of the Serb.
Nadal draws level with rivals Djokovic and Roger Federer, who have also finished the year in top spot five times, and moves one behind six-time end-of-year No 1, Pete Sampras.
Nadal and Djokovic have been this year's two dominant players after winning two Majors each.
Djokovic won the Australian Open and Wimbledon with Nadal cleaning up at Roland Garros and the US Open.
Federer ends the season at number three for the second year running. The Swiss, who turned 38 in August, has cut down his Tour commitments to focus on events around Grand Slams.
He reached the semi-finals of the French Open where he lost to Nadal and the last eight at Flushing Meadows where he lost in five sets to world number 20 Gregor Dimitrov.
In between he lost an epic Wimbledon final against Djokovic, the first to be decided by a tie-break in the fifth set, suggesting that he still has hopes of a 21st major title in 2020.
Dominic Thiem, who took a set off Nadal in the final of the French Open, moves up to number four after reaching the final of the ATP Finals where he lost to Stefanos Tsitsipas.
The 21-year-old Greek closes the year at number six, just behind Daniil Medvedev, after his triumph in London.
Former world No 1 Andy Murray began the year ranked at 240th and the prospect of retirement.
As he struggled with surgery on a hip injury and the subsequent recuperation he had slipped to 503rd in September before a dramatic return to the courts, which produced a remarkable victory at the European Open in Antwerp, lifted him to a year-end 126th.
Top 20 in the ATP Tour's year-end rankings:
1. Rafael Nadal (ESP) 9 985
2. Novak Djokovic (SRB) 9 145
3. Roger Federer (SUI) 6 590
4. Dominic Thiem (AUT) 5 825
5. Daniil Medvedev (RUS) 5 705
6. Stefanos Tsitsipas (GRE) 5 300
7. Alexander Zverev (GER) 3 345
8. Matteo Berrettini (ITA) 2 870
9. Roberto Bautista (ESP) 2 540
10. Gael Monfils (FRA) 2 530
11. David Goffin (BEL) 2 335
12. Fabio Fognini (ITA) 2 290
13. Kei Nishikori (JPN) 2 180
14. Diego Schwartzman (ARG) 2 125
15. Denis Shapovalov (CAN) 2 050
16. Stan Wawrinka (SUI) 2 000
17. Karen Khachanov (RUS) 1 840
18. Alex De Minaur (AUS) 1 775
19. John Isner (USA) 1 770
20. Grigor Dimitrov (BUL) 1 747
91. Kevin Anderson (RSA) 610
99. Lloyd Harris (RSA) 576