INDIANAPOLIS — Helio Castroneves understands better than most how hard it is to win the Indianapolis 500.

The charismatic Brazilian won as a rookie in 2001 and then backed it up with a victory the next year, becoming only the fifth driver in the history of Indianapolis Motor Speedway to win two in a row.

Since then, six years have passed with no fence-climbing celebrations at Indy for "Spiderman."

"The first year was pretty tough," Castroneves said. "The second year was even tougher. The third year, I had like a bullet. This car was incredible, supersonic. I finished second. So, I learned that you can't let opportunities go by. You've got to go for it. That's what we're going to do this Sunday."

A win this year would be particularly significant for Castroneves. On Friday, federal prosecutors dropped the remaining tax-evasion conspiracy charge against him and his sister, clearing Castroneves of all the charges that once threatened to derail his career.

In just his third race since returning to the series, Castroneves will start from the pole today, with Penske Racing teammate Ryan Briscoe next to him in the middle of the front row. That 1-2 punch gives team owner Roger Penske a good shot at his 15th Indy win.

"We've got a good chance this year with two cars on the front row," said Penske, who last visited Victory Lane with Sam Hornish Jr. in 2006. "But, to win here, everything has to work perfectly, everything."

Penske had a 1-2 finish in 2003, with Gil de Ferran outdueling Castroneves. This time, Castroneves would love to give the team another sweep — only with himself out front. Rising star Briscoe could make that difficult.

Although Castroneves is the oddsmakers' favorite, Briscoe is the one who could give Penske a new face on the Borg Warner Trophy.

"Winning this race comes from the preparations and the lead-up to it, what you've done in the three weeks here," the Australian driver said. "I honestly feel as though we couldn't have done a better job this month. We've really got a good feeling with the car setup and what we need to do going into the race."

Good enough to go 1-2-3?

Penske has a third entry for the first time since 1994, when Al Unser Jr. gave him a win. Will Power, hired to fill in for Castroneves until his legal problems were resolved, was rewarded with a drive at Indy after Castroneves returned to the cockpit.

The Aussie, starting from the outside of the third row, might be the most motivated of the Penske drivers as the team has not guaranteed him any more races.