Singapore, Sep 16: Formula One defending champion Lewis Hamilton of Britain (Mercedes) won the Singapore Grand Prix (GP) on Sunday, making the most of his start from the pole position and strengthening his grip over the overall top spot.Hamilton, 33, clocked a time of one hour, 51 minutes and 11.611 seconds to extend his overall lead to 40 points ahead of his main title rival Sebastien Vettel of Germany (Ferrari), who came third after finishing a full 39.945 seconds slower than Hamilton."What a race... I'm spent! I was unlucky with the traffic, my heart was in my mouth for a minute... but I managed to get the pedal down," Hamilton said in an interview with Formula One.The 2018 championship leader claimed the 69th win of his career, his fourth here at the Marina Bay Street Circuit and his fourth in the last five races this season.After the race, Vettel explained that "Overall, we were not fast enough. We tried to be aggressive in the beginning, and it didn't work out."Max Verstappen of the Netherlands (Red Bull) finished second, 8.961 off the pace, making the most of a successful tyre-change strategy."The team had a great strategy. We tried to do our own race... very happy with second," Verstappen said.Mercedes' other driver, Valtteri Bottas of Finland, came fourth in Sunday's race, 51.930s off his teammates' pace, and is fourth in the general classification.Vettel's Finnish teammate Kimi Raikkonen finished the race in the fifth spot, 53.001 seconds behind the winner, maintaining third place overall.