Defending Daytona 500 champion Jamie McMurray scraped the wall in practice and will switch to a backup car for NASCAR's season opener. McMurray apparently drove over a broken brake rotor from his No. 1 Chevrolet, slicing his right-front tire and sending the car into the wall Saturday. McMurray was unharmed, but his car sustained some damage along the right side. McMurray's Earnhardt Ganassi Racing team decided to switch to the backup car, the one McMurray finished second in last April at Talladega. Read more: http://sports.espn.go.com/rpm/nascar/news/story?id=6116386
