Rafael Nadal was confirmed as the new world number one in the latest ATP tennis rankings published on Monday, pushing Novak Djokovic to second as Roger Federer drops to seventh.
Nadal has 11,160 points, just 40 ahead of Djokovic, who lost his grip on the top spot despite defeating the Mallorcan to win the China Open on Sunday.
Britain's Andy Murray, currently recuperating from back surgery, is third in the revised rankings but Swiss great Federer sinks one place from sixth to seventh.
Spain's David Ferrer remains at number four, just 185 points off Murray's tally, while Argentina's Juan Martin del Potro moves up two places to fifth after winning the Japan Open.
Since returning in February after seven months out with a left knee injury, Nadal, 27, has won 10 titles, including the French Open and US Open.
Until Sunday's loss to Djokovic, he had been unbeaten since Wimbledon, where he was a shock first-round loser to Belgium's Steve Darcis.
Nadal has previously had two stints at the summit of men's tennis. He first became number one in August 2008 and stayed there for 46 weeks, regaining top spot in June 2010 and adding 56 weeks to his tally.
ATP world rankings
1 Nadal, Rafael (ESP) 11,160 (+1)
2 Djokovic, Novak (SRB) 11,120 (-1)
3 Murray, Andy (GBR) 6,895
4 Ferrer, David (ESP) 6,710
5 Del Potro, Juan Martin (ARG) 4,925 (+2)
6 Berdych, Tomas (CZE) 4,610 (-1)
7 Federer, Roger (SUI) 4,515 (-1)
8 Wawrinka, Stanislas (SUI) 3,150 (+1)
9 Tsonga, Jo-Wilfried (FRA) 3,115 (-1 0
10 Gasquet, Richard (FRA) 3,095
11 Raonic, Milos (CAN) 2,815
12 Haas, Tommy (GER) 2,355
13 Isner, John (USA) 2,115 (+3)
14 Simon, Gilles (FRA) 2,095
15 Janowicz, Jerzy (POL) 2,060
16 Almagro, Nicolas (ESP) 2,030 (+1)
17 Fognini, Fabio (ITA) 1,885 (+2)
18 Nishikori, Kei (JPN) 1,840 (-5)
19 Robredo, Tommy (ESP) 1,830 (-1)
20 Anderson, Kevin (RSA) 1,775 (+1)