Ferrari's Fernando Alonso held off Sebastian Vettel's hard-charging Red Bull to win an incident-packed Singapore Grand Prix on Sunday and boost his chances of a third Formula One crown.

Championship leader Mark Webber finished third in the second Red Bull to increase his lead from five to 11 points in the standings with four races remaining.

The Australian again rode his luck, emerging unscathed from a collision with McLaren's Lewis Hamilton that forced his title rival to retire.

Webber has 202 points, Alonso moved up to second overall on 191 after two successive wins in Monza and Singapore, and Hamilton lies a further nine points adrift in third place.

Vettel sits one point further back and world champion Jenson Button, who finished fourth, rounds out the top five on 177 points.

A mere 25 points, the amount awarded for a victory, separates the top five.

Alonso won the scandal-tainted inaugural Singapore race for Renault in 2008 after his Brazilian teammate Nelson Piquet crashed deliberately to bring out the safety car and help the Spaniard win.

The safety car was again deployed this time but Alonso, starting aggressively from pole position, drove a brilliant race to hold off Vettel for 61 laps around the floodlit Marina Bay circuit.

After a gruelling two-hour street fight and an almighty last lap tussle, the double champion crossed the line just 0.2 seconds ahead of the German who had qualified alongside on the front row.

Starting the race in fifth place, Webber was the biggest winner of the day after gambling on an early pit stop during the first safety car period after three laps and working his way through the field for a well-earned podium.

Hamilton was the biggest loser, enduring his third retirement in four races.

The Briton thought he had passed Webber on turn seven following the second safety car period but was broadsided by the Australian going into the straight.

"I'm not really sure what happened," he said. "He was in my blind spot so I didn't even know he was still there.

"All I know is I went in, I didn't see anyone alongside me and the next thing I know is my tyre has blown and that's it."

The race ended in bizarre fashion with Heikki Kovalainen, already lapped, steered his flaming Lotus to the side of the finishing straight.

With smoke and flames billowing out behind him, the Finn jumped out and grabbed an extinguisher handed through the wire mesh to put out the fire himself as cars raced past.

Adrian Sutil brought Force India back among points after finishing eighth.

It was a mixed day for Force India as Sutil, who started on 16th from the grid, held his nerves to pocket four points from the race while his Force India teammate Vitantonio Liuzzi crashed out.

With this result, Sutil has moved up a place to ninth with 45 points in the drivers' championship and Force India are placed sixth in the constructors' championship with 62 points.