Potholes are not normally a hazard at a showcase American motor racing track - especially during the Daytona 500, NASCAR's premier event in Florida.
But the race was red-flagged twice after a hole opened and before Jamie McMurray won the season-opener from a a fast-finishing Dale Earnhardt Jr.
The circuit had been pounded by days of rain and rare cold conditions, contributing to a section of the surface lifting off in turn two of the Daytona International Speedway.
The pothole brought up the first red flag, which lasted for an hour and 40 minutes while the second held up racing for just under 45 minutes.
Earnhardt said he had warned NASCAR of the problem but was ignored.
