Helio Castroneves

IndyCar driver Helio Castroneves surprises fans with free fuel and prizes during an event before the Grand Prix of Houston. (Bob Levey / Associated Press / October 3, 2013)

The IndyCar series returns from a monthlong layoff with a doubleheader in Houston this weekend that could tighten the championship battle at the season finale in Fontana.

Helio Castroneves, a three-time Indianapolis 500 winner still seeking his first series title, holds a 49-point lead over two-time champion Scott Dixon.

Simon Pagenaud, Marco Andretti and reigning champion Ryan Hunter-Reay -- who are 70, 71 and 74 points behind Castroneves, respectively -- still have an outside shot as well.

They'll try to close the gap in two separate races Saturday and Sunday on a 1.69-mile street circuit in Houston's Reliant Park.

Points are awarded on a sliding scale according to a car's finish, and the winner can earn up to 54 points in a single race by also leading the most laps and winning the pole position.

IndyCar has been idle since its street race in Baltimore on Sept. 1, which Pagenaud won. After Houston, the series wraps up Oct. 19 with a night race on the fast, two-mile Auto Club Speedway oval in Fontana.

"We need to close the points gap [in Houston] and make sure we're in the championship fight for the last race at Auto Club Speedway," said Dixon, who won three consecutive races in July for the Target Chip Ganassi Racing team.

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