Dale Earnhardt Jr. looks at the damage to his car after he was involved in a crash Wednesday during at practice at Daytona International Speedway. The mishap knocked him off the Daytona 500 pole to the rear of the field for Sunday's race.

DAYTONA BEACH, Fla. — After winning the pole position for the Daytona 500, Dale Earnhardt Jr. downplayed the fairy-tale aspect of what it would be like if he won NASCAR’s biggest race 10 years after his father’s death at the track.

Earnhardt’s Daytona Speedweeks took a somewhat more nightmarish turn Wednesday, when he wrecked his primary race car in practice. Now he’ll have to start Sunday’s race from the back of the pack instead of leading the field to the green flag.

Even before he hit the track, Earnhardt felt the possibility of wrecking in Wednesday’s practice was an unnecessary risk.

“I didn’t feel good about getting out there practicing, and didn’t think I needed to be out there practicing,” Earnhardt said. “I just had a bad feeling about it. We come running up on some guys that didn’t have their heads on straight and got into an accident.”

Despite wrecking his second car of Speedweeks, Junior still could win Daytona — he’ll just have his work cut out for him.

“We’ve got plenty of race cars,” Earnhardt said. “I ain’t worried about how fast we’ll be or whether we’ll be as good. We’ll be fine. But it never feels good tearing them up.”

Earnhardt mangled his pole-winning car, colliding with five-time defending NASCAR champion Jimmie Johnson and sliding into a wall.

Earnhardt was pushing his Hendrick Motorsports teammate in a two-car draft when Johnson had to back off the gas for slower-moving traffic in front of him. Earnhardt plowed into Johnson’s back bumper and nearly spun him out, but Johnson saved his car from skidding.

A second pack of cars led by Martin Truex Jr. closed quickly on Earnhardt’s bumper, causing the No. 88 Chevrolet to spin across the track and into the inside wall.

Johnson said he had to slow down suddenly when a pack of three cars ahead of them on the track drifted high from the bottom of the track toward the top.

“I was running out of space, and I thought that hole was going to close, and I lifted, and I got turned sideways from behind,” Johnson said.

The accident was largely a function of the two-car drafting style that has become the fastest way around Daytona International Speedway this year. Working together, two cars are so much faster than a single car or a larger pack that Earnhardt says other drivers have to watch the closing speed of the cars coming up behind them.

“You’ve got to pay attention out there, man,” Earnhardt said. “You want to come out here and race, you’ve got to pay attention.”

Hendrick Motorsports immediately pulled out a backup car for Earnhardt. He will have to forfeit the top starting spot in his qualifying race today and Sunday’s season opener.

Earnhardt’s wreck wasn’t the only big development in an eventful Wednesday at Daytona, where NASCAR continued to tinker with its rules.

The track opened with NASCAR officials ordering a change to the restrictor plate designed to back speeds off the 206 mph mark reached earlier in Speedweeks. The move to a smaller plate is expected to slow cars by 2-3 mph when they are drafting.

Michael Waltrip topped 206 in last weekend’s exhibition Budweiser Shootout.

“I don’t think you are going to hear one driver complain about that because it isn’t going to affect the racing,” defending Daytona 500 champion Jamie McMurray said. “You really can’t tell in the car, when everyone is moving the same speed.”