Danica Patrick wrecked just minutes into what turned into a dicey first practice session at Bristol Motor Speedway.
At least four drivers had to pull out their backup cars before the halfway point of Friday's 90-minute first practice.
Patrick lost control roughly three minutes into the session and slammed into Parker Kligerman's car. His Swan Racing team appeared to be trying to fix his Toyota, but Stewart-Haas Racing immediately pulled out the backup Chevrolet for Patrick.
Justin Allgaier then hit the wall, and so did Kyle Busch. Moments later, Greg Biffle crashed. All three went to backup cars.
Denny Hamlin watched the first 15 or so minutes of practice from pit road and speculated increased speeds from NASCAR's new aerodynamic rules was leading to the crashes at the 0.533-mile bullring.