Federer confirmed as oldest World No.1

Roger Federer officially returned to world number one as the latest ATP rankings were released on Monday, replacing old rival Rafael Nadal at the summit.

Roger Federer officially returned to world number one as the latest ATP rankings were released on Monday, replacing old rival Rafael Nadal at the summit.

The 36-year-old, who beat Andre Agassi's record as the oldest-ever No.1 en route to winning the Rotterdam Open title last week, will now look to stretch his lead over Nadal before the start of the claycourt season.

"It's unbelievable to be number one again after all these (six) years -- this is one of the best weeks of my life," 20-time Grand Slam champion Federer said after beating Grigor Dimitrov in Sunday's final.

Bulgarian Dimitrov's run to the final took him up one place to fourth above Alexander Zverev, while South Africa's Kevin Anderson broke into the top 10 for the first time after winning the New York Open.

ATP Top-20 1. Roger Federer (SUI) 2. Rafael Nadal (ESP) 3. Marin Cilic (CRO) 4. Grigor Dimitrov (BUL) 5. Alexander Zverev (GER) 6. Dominic Thiem (AUT) 7. David Goffin (BEL) 8. Jack Sock (USA) 9. Kevin Anderson (RSA) 10. Juan Martin del Potro (ARG) 11. Pablo Carreno Busta (ESP) 12. Sam Querrey (USA) 13. Stan Wawrinka (SUI) 14. Novak Djokovic (SRB) 15. Nick Kyrgios (AUS) 16. Lucas Pouille (FRA) 17. Tomas Berdych (CZE) 18. John Isner (USA) 19. Albert Ramos-Vinolas (ESP) 20. Andy Murray (GBR)