NASCAR season's first opening practice for the Sprint Unlimited was interrupted by a five- car crash at Daytona International Speedway on Friday.

Mat Kenseth triggered the incident, as pack of seven cars coming out of turn four Kenesh hit Busch, whose car slammed into Daytona's outside wall, forcing the three drivers to use their backup cars for the preseason race. Kurt Busch, Carl Edwards, Mark Martin and Juan Pablo Montoya were also involved in the crash.

Kenseth admitted fault stating, "That was 100 percent driver error, my driver error. I had no idea anybody was there and he had a run at the same time and I came down in front of him and he couldn't get slowed up from staying out of me. It was a hundred percent my fault."

Busch, Edwards and Martin will use their backup cars for Saturday night's 75-lap race. Kenseth and Montoya's teams were able to repair their primary cars.

"It's tough," Busch said. "A lot of hard work goes into these cars, and six weeks of preparation can be trashed in six laps."

"I didn't see anything," Edwards said of the incident. "I should have been listening to my spotter, Jason Hedleski, because he said, 'watch 'em, watch 'em' about two seconds before this happened."

The car wreck occurred in less than 10 laps into the first practice of Speedweeks. The remaining Daytona practice session went on without any incident. NASCAR's new Generation-6 race car is debuting in the race as well. Drivers and teams have been pleased with the new car after extensive testing during the offseason.