Title contenders prepare for one final showdown

Six drivers go into Sonoma with a shot at the 2015 Verizon IndyCar Series championship. With double points up for grabs, Juan Pablo Montoya's 34pt advantage is far from a comfortable position heading into this 85-lapper as the loss of Justin Wilson also weighs heavy in the back of everyone's minds.

Bonus points: Pole (1), Lap led (1), Most laps led (2)

Now for a look at the contenders and what they must do to take the Astor Cup for themselves.

Juan Pablo Montoya, starting 5th (Team Penske)

As the points leader, Montoya gets to play defense and with the gap he currently holds, JPM needs to aim for a podium. A top three finish means he is the champion, no matter what the other challengers do. He and main title rival Graham Rahal will start the race side-by-side in the third row. The 2015 Indianapolis 500 winner has led the standings from the very first race - never at any point did he relinquish it through the first 15 rounds.

Graham Rahal, starting 6th (Rahal Letterman Lanigan Racing) (-34pts)

Rahal has been the comeback story of 2015. He rose from years of mediocrity to be a formidable opponent at every event this season. He is without a doubt Montoya's biggest threat and also Honda's only shot. A 34 point deficit would be a near-insurmountable task to make up in any standard race, but this is no standard points race. His main disadvantage may be a lack of teammates, but you can expect that nearly every single Honda driver in the field will become his teammate to some extent on Sunday.

What he has to do: If he wins, Montoya must be no higher than fourth. Ninth is the lowest he can finish and still possibly win the championship, but that would mean that Montoya has to finish last. 

Scott Dixon, starting 9th (Chip Ganassi Racing) (-47pts)

Dixon has been around the block a few times with three titles and 37 wins to his credit over a career that dates back to 2001. Dixon is 47 points behind and needs an impeccable race. Even if he were to make up the gap to Montoya, he still has a 13 point deficit to Rahal that needs taking care of. Nonetheless, it would be unwise to discount Dixon at any point in a title fight.

What he has to do: If he were to win the race and take all the bonus points, Montoya must not finish inside the top five. Being within 20 points of Rahal, a win would guarantee that he'll leap ahead of him. Dixon will start ninth.

Will Power, starting 1st (Team Penske) (-60pts)

The reigning series champion hasn't been running at the level we're used to seeing him at this season, but he did earn pole position at Sonoma, taking that crucial bonus point away from the other contenders. Luck has not been on his side as of late ... Power has just two finishes higher than tenth in the last eight races.. Being fourth in points and 60 back of the lead, he'll need some bad luck to befall those he is chasing as well.

What he has to do: If he can get max points and win the race, he will still need Rahal to finish third or worse and Montoya to finish 10th or worse.

Helio Castroneves, starting 15th (Team Penske) (-77pts)

Yes, three of the six drivers still eligible for the crown belong to the Captain. Helio is down in fifth, a distant 77 points off his Colombian teammate. The Brazilian is considered by many to be the best driver never to be crowned champion. During his illustrious career, Castroneves has been second four times. But in 2015, he has yet to even win a race - the only one of these six drivers with a goose egg in the win column.

What he has to do: Even if he can come from 15th on the grid to win the race and lead the most laps, Montoya has to have a dreadful day (17th or worse) and Rahal can finish no higher than sixth.

Josef Newgarden, starting 2nd (Carpenter Fisher Hartman Racing) (-87pts)

Newgarden is not ignorant to his situation. He'll need a more than a little luck and a perfect race being 87 points behind and having five drivers between himself and the trophy. But he's still got a chance and will start the finale from the outside of the front row. Newgarden, like his fellow American Rahal, has had a career season. He finally captured that overdo first win and event went on to win again. His results are rather sporadic and unpredictable though with four finishes of 20th or worse to go with four finishes of second or better.

What he has to do: He will need nothing short of a miracle to take this title - If he were to win the race and lead the most laps, he needs Montoya 24th or 25th, Rahal ninth or worse, Dixon fifth or worse, Power third or worse, and Castroneves second or worse. All that is assuming the other five also fail to lead a lap.