Spanish tennis player Rafael Nadal remained in the number one spot on the men's Association of Tennis Professionals world singles rankings released on Monday, while Belgian David Goffin entered the Top 10 list.Nadal, 16-time Grand Slam champion, maintained the top spot after claiming the China Open title for the second time in his career on Sunday, reports Efe news agency.Switzerland's Roger Federer came in second, ahead of the United Kingdom's Andy Murray and German Alexander Zverev, respectively.Swiss Stan Wawrinka jumped to the eighth spot, while Bulgarian Grigor Dimitrov dropped to the ninth.Goffin went up one position to complete the Top 10 list after he claimed the Japan Open title, while Pablo Carreño Busta left the list.