Dale Earnhardt Jr. wrecks car

DAYTONA BEACH, Fla. -- Dale Earnhardt Jr., who won the pole for the Daytona 500 in Pole Day qualifying three days ago, will start in the back on Sunday.

Earnhardt was involved in an accident during practice Wednesday and will go to a backup car. He will start his qualifying race Thursday in the back but cannot improve his position for the Daytona 500.

Since the front row is locked in on Pole Day, Earnhardt can't improve his starting spot in the qualifying race, something every other driver can do except Jeff Gordon, who also earned a front-row spot. The rest of the grid positions are set in the two 60-lap qualifying races Thursday.

Earnhardt was running in a two-car tandem Wednesday with teammate Jimmie Johnson when the accident occurred exiting Turn 4. Johnson checked up because three slower cars -- driven by Robby Gordon, David Gilliland and Michael Waltrip -- were veering over in front of him.

When Johnson slowed to avoid hitting them, his car got loose. Earnhardt slowed down and was hit from behind by Martin Truex Jr. Earnhardt and Truex slid down the track and Earnhardt hit the inside retaining wall. The back sheet metal panel of Earnhardt's car was torn off.

"I don't know what's going on there," Earnhardt said. "Jimmie lifted and I got off the gas. We ran up on guys who didn't have their heads on straight.

"The closing rate for two-car tandem is so much faster. You've got to pay attention out there, man. If you're gonna race, you've got to pay attention. It's just hard," he said.

Earnhardt said he was hesitant about participating in Wednesday's first practice, which was delayed because of rain.

"I didn't feel good out there in practice today," Earnhardt said. "I just had a bad feeling about it. But we have plenty of race cars. It's never a good thing tearing them up, but we'll be fine."

Terry Blount is a senior writer for ESPN.com.