Jenson Button was a relieved man Sunday after clawing his way to fifth in the Singapore Grand Prix to maintain his grip on the world championship lead.

The Briton started from 11th on the grid but benefited from pit-lane penalties for other drivers and a safety car intervention to claim four unexpected points.

His nearest rival, team-mate Rubens Barrichello, came sixth so dropped a point, while Red Bull's Sebastian Vettel, the only other driver who can still catch him, came fourth.

But with just three races to go, Button now has a 15 point lead on Barrichello and a 25 point advantage over Vettel.

"It was a good day for us," Button, who drives for Brawn GP, told BBC Sport.

"I'm happy to get fifth, which is four points, and pull one off Rubens and only lose one to Sebastian Vettel. It was a good race. I go to Japan very positive for the next race."

Button had a torrid time in qualifying, struggling with handling problems, and said he wished he had started higher on the grid.

"I wish I did those laps in qualifying. That's the frustrating thing," he said.

"It would have made life easier for me in the race. I got stuck behind Heikki Kovalainen for quite a few laps, but when he pitted I was able to get past him.

"I could see Rubens pulling away because he was stopping four or five laps shorter than me but I couldn't do anything. It's difficult because when you're that close behind someone you lose downforce."

Whoever wins the drivers' championship, it looks certain that the constructors' championship will go to Brawn GP in the outfit's first season.

The team has 153 points to Red Bull's 110.5 and Ferrari's 62.

Team principal Ross Brawn was delighted to salvage some points after the dismal qualifying campaign.

"It was a recovery for us," he told reporters.

"It looked pretty grim on Saturday afternoon but the team did a great job to salvage what we did yesterday. Our main competitors did not do that."