Serbias star Novak Djokovic has maintained the No. 1 spot in the mens Association of Tennis Professionals world singles rankings released on Monday with 8,045 points.Djokovic snatched the top spot from Spanish tennis great Rafael Nadal after his retirement from the Paris Masters due to abdominal problems.Roger Federer of Switzerland remained world No. 3 ahead of Argentinas Juan Martin del Potro in this weeks unchanged rankings.Meanwhile, Argentine Guido Pella jumped seven places up to world No. 58 thanks to his victory at the Uruguay Open on Sunday.The current top-10 ATP rankings and point scores are as follows:1. Novak Djokovic (Serbia) 8,045 points2. Rafael Nadal (Spain) 7,4803. Roger Federer (Switzerland) 6,0204. Juan Martin del Potro (Argentina) 5,3005. Alexander Zverev (Germany) 5,0856. Kevin Anderson (South Africa) 4,3107. Marin Cilic (Croatia) 4,0508. Dominic Thiem (Austria) 3,8959. Kei Nishikori (Japan) 3,39010. John Isner (United States) 3,155.