SINGAPORE - The searing pace of the Red Bulls was evident again on Saturday as championship leader Sebastian Vettel topped the timesheets in the third and final practice session ahead of the Singapore Grand Prix.Vettel, who holds a 53 point lead over Ferrari's Fernando Alonso with seven races remaining this season, clocked a best time of 1min44.173 seconds in the hour session.GOOD FORMRomain Grosjean showed some good pace throughout the session in his Lotus to finish second fastest, 0.191 seconds behind Vettel as the sun set on another hot and humid day in Singapore.Nico Rosberg was third quickest in his Mercedes (1min44.741) but the German was more than half a second slower than Vettel, who had enjoyed a similar advantage after second practice on Friday.Vettel's Red Bull team mate Mark Webber was fourth fastest with 2008 world champion Lewis Hamilton fifth for Mercedes as the cars set up to make the most of the high downforce layout in Singapore dominated again.Vettel, winner of the last two races at the Marina Bay Street Circuit, had predicted on Friday a close challenge from Mercedes during qualifying, which was scheduled to begin at 1300 GMT.Spaniard Alonso was sixth fastest for the second consecutive session, more than a second down on Vettel.Alonso's Brazilian team mate Felipe Massa was 10th quickest while Kimi Raikkonen, who will join the Spaniard at the Italian team in 2014, was down in 12th for Lotus. 3rd and Final Free Practice Session from the F1 Singapore Grand Prix at Marina Bay Street Circuit1. Sebastian Vettel (Germany) RedBull - Renault 1:44.173 2. Romain Grosjean (France) Lotus - Renault 1:44.364 3. Nico Rosberg (Germany) Mercedes 1:44.741 4. Mark Webber (Australia) RedBull - Renault 1:44.906 5. Lewis Hamilton (Britain) Mercedes 1:44.921 6. Fernando Alonso (Spain) Ferrari 1:45.257 7. Sergio Perez (Mexico) McLaren 1:45.500 8. Nico Huelkenberg (Germany) Sauber - Ferrari 1:45.876 9. Jenson Button (Britain) McLaren 1:45.890 10. Felipe Massa (Brazil) Ferrari 1:45.935 11. Jean-Eric Vergne (France) Toro Rosso - Ferrari 1:46.084 12. Kimi Raikkonen (Finland) Lotus - Renault 1:46.147 13. Pastor Maldonado (Venezuela) Williams - Renault 1:46.338 14. Daniel Ricciardo (Australia) Toro Rosso - Ferrari 1:46.358 15. Valtteri Bottas (Finland) Williams - Renault 1:46.660 16. Paul Di Resta (Britain) Force India - Mercedes 1:46.879 17. Esteban Gutierrez (Mexico) Sauber - Ferrari 1:46.893 18. Adrian Sutil (Germany) Force India - Mercedes 1:47.249 19. Giedo van der Garde (Netherlands) Caterham - Renault 1:48.931 20. Charles Pic (France) Caterham - Renault 1:49.037 21. Jules Bianchi (France) Marussia - Cosworth 1:49.182 22. Max Chilton (Britain) Marussia - Cosworth 1:49.982 Stay with Wheels24 for the 2013 Singapore GP weekend.