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Dan Wheldon leads the pack during the final IRL race of the season.

updated 5:48 p.m. ET Sept. 10, 2006

JOLIET, Ill. - Sam Hornish Jr.’s strategy was simple: Stay out of trouble and avoid mistakes.

He did just that Sunday and claimed his third IRL series championship.

While Dan Wheldon beat Target Chip Ganassi teammate Scott Dixon by 0.1897 seconds to win the PEAK Antifreeze Indy 300 at Chicagoland Speedway, Hornish finished third, 0.2323 seconds behind. But he celebrated a championship.

“I can’t think of how next year could be any better, but hopefully, it is,” said Hornish, the series winner in 2001 and 2002 for Panther Racing.

Hornish and Wheldon finished the season with 475 points, but Hornish had four victories — two more than Wheldon. And he did enough Sunday to give Marlboro Team Penske owner Roger Penske his first title and claim a $1 million bonus.

“When we came over to the IRL, our goal was to win a championship,” Penske said. “The guy sitting on my right (Hornish) beat us the first two years — beat us like a drum. To get him on the team and then deliver here is pretty special. ... This is another one for the record books. But we’ve got to do it next year.”

The day began with Penske driver Helio Castroneves holding a one-point lead over Hornish with 431, with Wheldon and Dixon 19 and 21 points back, respectively. Castroneves was fourth on Sunday and finished the season with 473 points, while Dixon was fourth at 460.

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With thick clouds hanging above after a rainy morning, the race started on time.

With no margin for error, Castroneves committed a speeding violation early on in the pit and moved to the back of the pack. The two-time Indianapolis 500 winner was in fourth after 62 laps, but he was in danger of falling out of contention before a yellow flag with 50 laps to go.

“I still don’t understand about the speed-limit violation,” said Castroneves, who had four victories this season but is still seeking his first IRL title. “I still think it wasn’t me. If I was penalized, I’m sure someone (else) should have been because I was following with a lot of people.”

With about 30 laps left, Wheldon and Dixon began trading leads, one refusing to yield to the other. Not with the championship at stake — and not with Hornish right behind.

Wheldon felt he needed the three bonus points for leading the most laps, so he was aggressive from the start. The same goes for Dixon.