SINGAPORE (Reuters) - Britain’s Lewis Hamilton eased to victory from pole position at the Singapore Grand Prix on Sunday as the Mercedes driver extended his championship lead over Ferrari’s Sebastian Vettel to 40 points with six rounds remaining.

Formula One F1 - Singapore Grand Prix - Marina Bay Street Circuit, Singapore - September 16, 2018 Mercedes' Lewis Hamilton celebrates after winning the race REUTERS/Edgar Su

Hamilton held off a mid-race challenge from Red Bull’s Max Verstappen to register a record-equaling fourth triumph at the floodlit Marina Bay Street Circuit track, while Vettel finished third to slip further behind in the title race.

“Great job everyone, what a weekend... keep pushing, keep pushing, we’ve got this,” Hamilton told his team over the radio soon after crossing the line at the end of the 61st lap.

Hamilton’s 69th overall victory was his seventh of the season and it was built on the foundations of a stunning qualifying lap on Saturday, when he stormed to pole in a car deemed inferior to the Ferraris and Red Bulls on this circuit.

For Vettel and Ferrari it was another disappointing weekend after the car showed plenty of pace through all three practice sessions, the German’s cause not helped by a questionable strategy and a poor pitstop.

Hamilton won this race from the third row a year ago when Vettel, Verstappen and Kimi Raikkonen collided before Turn One but there was no repeat of such drama this time after the drivers got off to a clean start at the head of the field.

There has, however, been a safety car period in every race in Singapore since it joined Formula One in 2008 and it was deployed on the opening lap after Sergio Perez pushed his Force India team mate Esteban Ocon into a wall after Turn Three.

“Sorry guys there was no room,” Perez told his team over the radio.

Vettel got past Verstappen before the safety car emerged and slotted in behind Hamilton, but his race unraveled when the German pitted first on the 14th lap but got stuck in traffic and overtaken by the Dutchman when he made his stop for fresh tires.

BACK MARKERS

Hamilton was cruising up front but suffered a mini-crisis on the 38th lap when he got stuck in a queue of tail-enders, which allowed Verstappen to get right up behind him.

The Dutchman had a look up the inside as Hamilton struggled to pass the back markers but the Briton just stayed ahead and was able to pull clear all the way to the checkered flag once he had a clear track ahead of him.

“It definitely got a little bit interesting toward the end with the back markers as you could already feel the draft from the cars when you were five and six seconds behind,” Hamilton added.

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“And you can’t really see the blue flags (telling back markers to move aside), they are quite dark.”

Hamilton’s team mate Valtteri Bottas held off a prolonged late challenge from Raikkonen in the other Ferrari to claim fourth place, the pair finishing just ahead of Red Bull’s Daniel Ricciardo, who was closing on them in the final laps.

McLaren’s Fernando Alonso came home in seventh, with Renault’s Carlos Sainz and Nico Hulkenberg claiming eighth and 10th respectively, either side of Sauber’s Charles Leclerc.

“Overall we had a very strong package, both Kimi and myself looked very competitive throughout practice, but in the end, the race result, we finished third and fifth,” Vettel said.

“Like yesterday, not where the speed of our car belongs.”