A multi-car wreck Wednesday morning at Daytona International Speedway caused heavy damage to six cars, including four-time defending Sprint Cup champion Jimmie Johnson's Lowe's Chevrolet. The wreck, one of several incidents and near-incidents in a frenetic session, was set off when Mike Bliss lost control on the low side of the track in front of a pack of cars coming out of Turn 4 and collected Joey Logano's Toyota. As the rest of the field took evasive action, Johnson rear-ended Denny Hamlin.

"When he checked up, I got into him really hard," Johnson said of Hamlin. "It did some damage to the front end of the car and we just can't get it 'right' here."

Johnson will now switch to the car he raced in last Saturday's Budweiser Shootout.

"We know we've got a great racecar in the truck," he said of the backup. "We'll bring it out and send this one back to Charlotte and let it be repaired the right way in Charlotte in case we need it after the Duels. So, we have a good strategy. We certainly wanted to keep this car and, from the outside, it doesn't look all that damaged, but the nose is twisted and it just needs to be right if we're going to have it for a backup down here."

During the first practice of the day, Clint Bowyer cut a tire and got collected by Derrike Cope and David Reutimann, the three of them sustaining major damage to their cars and being forced into their back-ups.

Brian Vickers also spun during the day's first practice, while Dale Earnhardt Jr. and Jamie McMurray almost caused a major pile up when they made slight contact at the sharp end of the drafting group later in the same session.

Many drivers have chosen to do very limited running to avoid damaging their primary car for Sunday, as in five practice sessions that have taken place so far, there have been frequent incidents involving several drivers.

"I thought things were wild," Johnson added. "And here's the biggest problem. Guys have different theories on where they want to blend on the race track. Some people stay on the bottom; others think they blend on the top. Either way there is a draft of 18 to 20 cars coming and we're like a snake weaving through these cars, and cars coming in and off at different speeds.

"I don't believe that's what caused this wreck, but there were a lot of other crazy moments because of that. I need to go to the tape and see what happened here because I was just riding along and thought everything was fine, and the next thing you know, I was in the middle of it."

Matt Kenseth and Marcos Ambrose set the fastest times in the two sessions, followed by Kyle Busch, who was second fastest in both.