Race leader Denny Hamlin missed pit road. Darlington is a tricky track, and Hamlin was coming in for what he hoped was his final stop of the race when he missed the pits. He was coming in wide and locked up his tires when he noticed he was going to miss it, but it was too late. He had to go around one more time to get back into the pits and the self-inflicted stop-and-go destroyed his lead.
With the race winding down, this mistake may have sealed his fate. Unless he has one more killer move left in him after his overtime run in the Xfinity race.
Related: Denny Hamlin pulls off incredible cross over move to win at Darlington in overtime