Paris - Rafael Nadal regained the No 1 spot ahead of the French Open in the world rankings on Monday after winning his eighth Rome Masters title.
The victory saw Nadal overtake Roger Federer, who is not playing the claycourt season this year.
Former No 1 Novak Djokovic continued his fall, slipping four places to 22nd.
Top 20 in the latest ATP Tour rankings:
1. Rafael Nadal (ESP) 8 770
2. Roger Federer (SUI) 8 670
3. Alexander Zverev (GER) 5 615
4. Marin Cilic (CRO) 4 950
5. Grigor Dimitrov (BUL) 4 870
6. Juan Martin Del Potro (ARG) 4 450
7. Kevin Anderson (RSA) 3 635
8. Dominic Thiem (AUT) 3 195
9. David Goffin (BEL) 3 020
10. John Isner (USA) 2 955
11. Pablo Carreno (ESP) 2 415
12. Diego Schwartzman (ARG) 2 165
13. Sam Querrey (USA) 2 140
14. Roberto Bautista (ESP) 2 120
15. Jack Sock (USA) 2 110
16. Lucas Pouille (FRA) 2 030
17. Kyle Edmund (ENG) 1 950
18. Tomas Berdych (CZE) 1 900
19. Fabio Fognini (ITA) 1 895
20. Hyeon Chung (KOR) 1 775
Selected:
22. Novak Djokovic (SRB) 1 665
32. Richard Gasquet (FRA) 1 395
37. Jo-Wilfried Tsonga (FRA) 1 245