Two weeks ago, Castroneves came to Houston for IndyCar's doubleheader weekend with a season-high 49-point advantage over Dixon. Castroneves had scored 12 straight top-10 finishes, including a victory in June at Texas Motor Speedway, but the Team Penske driver had a frustrating weekend in Houston, finishing 18th in the first race and 23rd in the second event. He experienced a gearbox problem in the early going of each race.
Dixon finished first and second at Houston. If Dixon finishes fifth or better in Fontana, he will clinch his third IndyCar championship, regardless of what Castroneves does. The Chip Ganassi Racing driver won the series title in 2003 and '08.
"I think for us the easiest way to approach it is how we typically approach a race weekend, and that's to go there setting our sights on winning it," Dixon said. "If we can achieve that, then it makes the championship story just sort of unfold. It'll be a tough situation...It's not going to be easy by any means and something that we're going to have to fight to the bitter end. We'll go into the weekend obviously trying to achieve a win."
Dixon won his previous championships five years apart. It's been five years since his most recent title.
"You can't rely on stats like that, especially for us," he said. "Every year we compete, we try to win the championship, and I think definitely over the last five or six years we've had a good shot sort of going into the last one each of those years."
In 2009, Dixon entered the season-finale in Homestead, Fla. with a four-point lead over Dario Franchitti, his teammate at Ganassi, but Franchitti claimed the championship by winning the race there. He concluded the season with an 11-point margin over Dixon, who finished third in the race.
Castroneves has yet to win an IndyCar championship. He finished second in the standings in 2002 (20 points behind Sam Hornish Jr.) and '08 (17 points behind Dixon).
"At this point, I feel that I have nothing to lose, so there is no pressure, to be honest, you just go for it," Castroneves said. "We're going to look for our best result, and on the ovals, try to replicate what we did in Texas, and hopefully we'll be successful."
Last year, IndyCar competed at this two-mile Southern California racetrack for the first time since 2005. Ed Carpenter won the race, while Dixon finished third and Castroneves placed fifth. Ryan Hunter-Reay's fourth-place run allowed him to clinch the title. Hunter-Reay beat Will Power by only three points. Power finished 24th after crashing early in the event.
Three weeks ago, several IndyCar teams participated in a manufacturers' test at Auto Club Speedway.
"We had a fantastic test, and we were really fast," Castroneves said. "I was extremely happy with the performance of the car in Fontana. We just hope we continue with that, and it will bring us a successful result."
The manufacturers' championship is still very much up for grabs. Chevrolet and Honda are tied in points. Both took their ninth win of the season by splitting the doubleheader in Houston.
Alex Tagliani will substitute for Franchitti in Ganassi's No. 10 car. Franchitti suffered multiple injuries during an accident on the final lap of the second Houston race.
On Friday, Andretti Autosport announced that Carlos Munoz will take over for E.J. Viso in the No. 5 car for this race. Viso is absent due to an undisclosed illness. Munoz, an Indy Lights competitor, has competed in two IndyCar races this season. He started and finished second in the May 26 Indianapolis 500.
Twenty-five teams are on the entry list for the MAVTV 500.
Series: IZOD IndyCar. Date: Saturday, Oct. 19. Race: MAVTV 500. Site: Auto Club Speedway. Track: 2-mile oval. Start Time: 8:30 p.m. ET. Laps: 250. Miles: 500. 2012 Winner: Ed Carpenter. Television: NBC Sports Network. Radio: IMS Radio Network/SIRIUS XM Satellite.