Lewis Hamilton won the floodlit Singapore Grand Prix from pole position on Sunday to extend his championship lead over Sebastian Vettel to a commanding 40 points.

The Mercedes driver made a clean start and was largely untroubled as he beat Red Bull driver Max Verstappen by nine seconds, with Vettel much further back in third.

"I definitely didn't come to Singapore thinking I'd come away with 10 points more (than Vettel)," a jubilant Hamilton said. "I know I can't get ahead of myself, we can't get ahead of ourselves."

The four-time Formula One champion recorded his seventh win of the season and 69th of his F1 career. Vettel's championship bid crumbled when he crashed from pole here last year and then went on to lose the title by 46 points to Hamilton.

It is looking increasingly like a repeat scenario for the Ferrari driver, who now has just six races left to catch Hamilton in their bid for a fifth F1 title.

Vettel was unhappy with his team after qualifying in third place behind Verstappen, and the German driver sounded irritated during Sunday's race after a team strategy error to send him into the pits for a tire change before Hamilton failed to work.

Instead he lost position and crucial points, dropping back behind Verstappen having earlier overtaken him.

"We tried to be aggressive in the beginning and obviously it didn't work out," a despondent Vettel said. "I think today, with the way we raced, we didn't have a chance. I said before the weekend we can only beat ourselves and today we didn't get everything out of the package."

Hamilton has won four of the past five races and leads Vettel 7-5 in wins this season.

The only thing bothering Hamilton seemed to be the sweltering conditions. Despite the night-time start, the temperature was around 30 degrees Celsius (86 Fahrenheit) and the humidity intense, meaning drivers lost up to nine pounds in fluids.

"I'm spent," Hamilton said moments after victory, crouching down by his car.

His teammate Valtteri Bottas was fourth ahead of Ferrari's Kimi Raikkonen and Red Bull's Daniel Ricciardo. Two-time F1 champion Fernando Alonso, who won the inaugural race here 10 years ago, was seventh for McLaren in his final F1 season.

Hamilton's stunning pole on Saturday night was a record-extending 79th in F1 and among his best.

"It's so hard to overtake here," Hamilton said. "So positioning is everything."

Vettel almost bumped into Verstappen as they headed into the first corner on Sunday, but they just avoided contact.

Moments later, Vettel got past Verstappen with a great move on Raffles boulevard while behind them Sergio Perez knocked his Force India teammate Esteban Ocon into the wall and out. The incident meant a safety car came out on to the track for four laps.

When the race re-started, Ferrari gambled on pitting first for new tires by bringing in Vettel first. Mercedes pitted Hamilton moments later, and when Vettel came back out he was still behind Hamilton and lost more time getting past Perez.

Verstappen was the next in, almost colliding again with Vettel into turn 3. Verstappen held position, Vettel dropping one place.

"No chance, we are again too late," Vettel complained over team radio, taking another apparent swipe at team strategy. "If (being aggressive) works it's great — today it didn't work by quite a bit."

Perez had another incident later in the race.

The Mexican driver got frustrated when stuck behind the Williams of Russian driver Sergey Sirotkin, and collided with him as he tried to pass. On Mexico's National Independence day, Perez crossed the line a lowly 16th, having also likely lost the team points when he knocked out Ocon.

Hamilton's only scare was when he was held up by Frenchman Romain Grosjean and Sirotkin as they scrapped for position near the back. It slowed him down and enabled Verstappen to close the gap, but the Dutchman couldn't quite get close enough to attack.

"The guys weren't letting me by," Hamilton said. "My heart was in my mouth for a minute."

Time is running out for Vettel, who realistically has to win in Russia in two weeks' time if he is to get back into title contention.