Sao Paulo, Brazil ? Formula One already has crowned Fernando Alonso as its 2005 champion, but the season is far from over.

The all-important constructors championship remains undecided, and there is still a lot at stake in the final two races in Japan and China. Some drivers still need to perform well to guarantee a ride for next year, and teams will keep looking to improve as they aim toward next season.

Renault’s Alonso won the driver’s title with a third-place finish in the Brazilian Grand Prix on Sunday, but McLaren dominated the race and took the lead in the constructors championship for the first time this season. Juan Pablo Montoya was first, and Kimi Raikkonen finished second, moving McLaren to 164 points against Renault’s 162.

“Congratulations to Fernando, but he better be prepared for me and the team to fight him hard for the rest of the season,” Raikkonen said. “I will now focus on winning the constructors title for the team and go flat out for the last two races.”

Alonso, who stayed out of trouble for most of the year while managing his advantage in the drivers championship, promised to be more aggressive from now on.

“We are ready to fight a bit less conservatively in the last two races,” said Alonso, who became F1’s youngest champion by clinching the title in Brazil. “I will be more aggressive with how I use the engine, the tires, every part of the car.”

Fernando Alonso, center, celebrates with members of his team after he was crowned world champion. Alonso placed third in the Brazilian Formula One Grand Prix on Sunday in Sao Paulo, Brazil.

The constructors championship is especially important because it determines the amount of money each team receives from F1’s governing body at the end of the season.

McLaren, an eight-time champion, is looking for its first title since 1998, while Renault has yet to win the title. Ferrari, which won the past six titles, is third in the standings with 98 points, 17 ahead of fourth-place Toyota.

“At the beginning of the year we probably lost the drivers championship to Fernando when he was stronger,” Montoya said. “But I think we deserve the constructors championship.”

McLaren, winner of the past five races, has had the fastest car throughout the year, but Renault was able to stay competitive because of its reliability.

Alonso failed to finish only two of 17 races, and reached the podium 13 times. McLaren, on the other hand, dropped out of several races when its drivers were ahead.

Only Renault and McLaren have a shot at the championship, but there is still a lot to be decided for other teams.

Williams, a nine-time constructors champion, still hasn’t picked its second driver for 2006, and the final two races could be crucial in the team’s decision. Test driver Antonio Pizzonia of Brazil will drive alongside Mark Webber in China and Japan, with a chance to show his potential and make a push for a full-season seat next year. He is fighting for a spot with Nico Rosberg, son of 1982 series champion Keke Rosberg.

Pizzonia has been replacing the injured Nick Heidfeld, who will move to the new BMW team in 2005.

BMW also has a seat open. Jacques Villeneuve, the 1997 F1 champion and a former Indianapolis 500 winner, could get the spot depending on his performance in his final races with Sauber. McLaren test driver Alexander Wurz also is a candidate.

Other teams, including Jordan and Minardi, also hope to use the final races to decide on their lineup for next year.

The Japanese Grand Prix takes place at the Suzuka track on Oct. 9, while the Chinese race is scheduled for Oct. 16 at the Shanghai International Circuit.