Michael Andretti says his title-contending driver Ryan Hunter-Reay is the underdog

Hunter-Reay's victory at Baltimore last weekend moved him to the top of the win-list for the season, with four victories compared to championship rival Will Power's three, although Power holds a 17-point advantage in the standings.

Andretti said that Power's points lead gives him a significant advantage at the Fontana showdown.

"We are in control of our own destiny a little bit, but all [Will] has to do is finish right behind us," he said. "So he's going to be racing us in that way. If we're running third, all he has to do is finish fourth and he's fine. Whereas we've got to go for the win, and hope that we have some help with a couple of guys between us. We're still going to need to have a really good race, and we need him to have just an average race."

Andretti also admitted to some engine concerns ahead of the race, with Hunter-Reay having used the last of his five permitted fresh engines at Baltimore.

With the teams scheduled to test at Fontana in the coming days - for which the same engine must be used - he said that the team is open to fitting a sixth Chevy unit for the race to safeguard against reliability problems and take the 10-place grid penalty that would accompany it.

"We're looking at that," he said. "We have a couple of tests, and we're going to look at how many miles we get on the tests, and there's a chance that we might have to take a penalty. But we don't know for sure yet."

The team's anxiety on that front will be tempered slightly by fact that Power is in a similar situation; the Team Penske driver having also run his fifth engine at Baltimore.