(AP) - An early-race accident in Sunday's NASCAR race at Kentucky ended Brad Keselowski's hopes of repeating as winner, and the quest now is maintaining hopes of defending his Sprint Cup championship. Keselowski was running near the top 10 on lap 49 when Kurt Busch's No. 78 Chevy went low, came back up the track and into his left rear quarter-panel. The contact spun the No. 2 Ford up the track in the front stretch and triggered a multicar wreck collecting five other cars. Greg Biffle's No. 16 Ford had nowhere to go and got the worst of it, slamming into Keselowski and lifting his car off the asphalt and into the outside retaining wall. Biffle's mangled car caught fire, but he and Keselowski weren't injured. The incident sent Keselowski's car to the garage and the driver later tweeted, "we ain't done." Busch apologized for causing the wreck.