(AGI) Rome, Sept 20 - Ferrari's Sebastian Vettel won his fourthSingapore Grand Prix on Sunday, finishing ahead of Red Bull'sDaniel Ricciardo and fellow Ferrari driver Kimi Raikkonen. Itwas Vettel's third victory this season, with the German racerstarting in pole position and leading the race from start tofinish despite two Safety Cars entering the track and reducinghis advantage. A good week-end for Ferrari but less so forMercedes, with Nico Rosberg coming fourth and world championLewis Hamilton being forced to retire. Williams-Renault'sValtteri Bottas took fifth, ahead of Red Bull's Daniil Kvyatand Force India's Sergio Perez. Max Verstappen and Carlos Sainzfollowed in their Toro Rossos, with Felipe Sauber's Nasrclosing the top ten. (AGI). .