INDIANAPOLIS (AP) — Brad Keselowski was rolling at this time last year.

He'd already won three races and stormed into the Chase for the Sprint Cup championship, where he went round for round with Jimmie Johnson and won his first title.

But after finishing 21st at the Brickyard on Sunday, he's suddenly worried about even having a chance to defend his title. Keselowski is 13th in the standings and winless, so not currently eligible for one of the two wild card berths.

Only the top 10 drivers in points and the two winningest drivers not already qualified for the Chase make the 12-driver field. There's six races left before the field is set.

"If you don't have concerns then your heart isn't in it," Keselowski said. "You should be concerned from Daytona on. When you have success, you lessen those concerns, and we have had some success this year, but we haven't had the wins and consistency to remove all of those concerns."

Keselowski said his Penske Racing team just hasn't been able to find a groove.

"It has been one of those years where when we have a car that is fast enough to contend and win races, it turns into a strategy race, and when we don't have car fast enough and we play strategy, it turns into a race like today where it was about speed," he said. "We haven't been able to catch it the right way. In reality we would like to be fast everywhere but that hasn't been the case for us. That is what we need to work on."

Keselowski said he still expects to have a chance at the end, but his confidence will need to be supported by at least one win. Tony Stewart and Martin Truex Jr. already had wins coming into Sunday's race, and Ryan Newman got his first win of the year at the Brickyard 400.

Keselowski will need to win at least one race, or crack the top 10.

"I am not going to say that I feel 100-percent about a lot of things, but I can say that I believe in the people I am around and we are going to get this right." he said. "It is just a matter of when."