Sao Paulo - Lewis Hamilton of McLaren-Mercedes on Sunday became the youngest-ever Formula One world champion at the age of 23, pipping Ferrari's Felipe Massa to the title thanks to a fifth-place finish in a thrilling Brazilian Grand Prix at Interlagos.

The Briton went into the final F1 race of the season with a seven- point lead over eventual race-winner Massa, and only needed to finish in the top five in Sao Paulo to take the title.

Hamilton appeared to be cruising to the title while running fourth in the closing stages but a late rain shower saw the leaders pit once again while Toyota's Timo Glock found himself in fourth after running the risk of staying out on dry tyres.

Toro Rosso's Sebastian Vettel then overtook Hamilton to leave the McLaren driver sixth going into the final lap, a result that would have handed Massa the title.

However, Glock couldn't hold on as the track conditions deteriorated and was passed by both Vettel and Hamilton.

Fernando Alonso of Renault came home second with Ferrari's Kimi Raikkonen third.

"I am just thankful and proud of the team and everyone around me who has given me the opportunity. It was a tough race, the toughest of my life," said Hamilton.

"I thought do I have it? Do I have it? And when they told me I was ecstatic."

Massa, meanwhile, tried to come to terms with coming so close to becoming the first Brazilian since Ayrton Senna in 1991 to lift the F1 title.

"I know how to win and I know how to lose and that is why I am here, but for sure I am very emotional," he said.

"We need to congratulate Lewis. He did a great championship and scored more points than us. He deserved to win, he's a great champion."

Hamilton finishes with 98 points after 18 races, one clear of Massa, while Ferrari take the constructors' title ahead of McLaren.

A sudden downpour also affected the start of the race, leading to a delay as the teams switched to wet tyres. Despite the tricky conditions, the front four all got off to a solid start with Massa, who started from pole, retaining top spot and Hamilton staying fourth.

However, Vettel and Alonso both managed to pass Hamilton's McLaren teammate Heikki Kovalainen, who dropped two places to seventh.

David Coulthard had a disappointing end to his F1 career as the Scot's race ended at the very first corner when his Red Bull collided with Nelson Piquet Jr's Renault.

The collision resulted in a safety car and when racing resumed Massa defended his lead. The Brazilian came in for dry tyres with 61 laps remaining but Hamilton stayed out a lap longer, as did Jarno Trulli and Raikkonen.

Hamilton returned just behind Trulli in seventh but a mistake by the Italian on the next lap saw the McLaren man move up one place to sixth with Giancarlo Fisichella of Force India in his sights.

Massa continued to lead in treacherous conditions but was being tracked closely by Vettel and Alonso.

Hamilton finally managed to get past Fisichella after 17 laps to move back up into the fifth place he needed to secure the F1 title.

Vettel was the first of the leaders to pit for a second time, coming in with 44 laps to go, returning to the track in sixth spot. Massa came in 10 laps later, changing to hard compound tyres, and was followed soon after by Hamilton, Alonso and Raikkonen.

While these drivers fuelled to the finish, Vettel needed one more stop, moving Hamilton up to fourth with 20 laps to go.

With the rain returning, Hamilton, Alonso and Raikkonen all pitted with five laps to go while Massa pitted a lap later.

Glock suddenly found himself up to fourth after taking the decision to stay out on dry tyres while Hamilton fought a losing battle with Vettel.

However, just as it looked like it would be Massa's day, Glock faltered to hand Hamilton the title on the last turn.

"Lewis passing Glock that mixed up a lot of emotions but that is racing and unfortunately we missed one point but that is racing and we need to be proud of our job and our racing," said Massa.

"We did everything perfect today but unfortunately it was not enough."

Hamilton, for his part, was just trying to come to terms with being F1 world champion at the age of 23 years and 300 days.

"It's pretty impossible to put into words," he said. dpa