Penske duo chasing crucial victory

Castroneves currently heads Hornish by just a single point going into the finale, with Chip Ganassi Racing teammates Scott Dixon and Dan Wheldon also in contention, 19 and 21 points adrift respectively.

With 50 points available for a win, and only 40 on offer for second place, both Penske drivers know that they cannot afford to take a conservative approach to the weekend.

"It's going to be a very exciting race with four guys, who all seem to do well on this type of track, fighting for the title," said Castroneves.

"I feel as though I need to win this race to win the championship, so we're going to give it our all.

"I've been chasing an Indycar championship my entire career, and have never been able to accomplish this goal, so winning it would be a dream come true."

Hornish took two wins at Chicagoland while driving for Panther Racing.

"Chicagoland Speedway is a track where I've always been strong, so I feel like we have a great opportunity to do well here," he said.

"With only a one point deficit in the championship, a win takes all, so that's what we're shooting for this weekend.

"To be honest, with some of the problems we've had at a couple of the races this year, I feel that we could've been a lot further behind; so I'm happy with where we are heading into the final race."