DARLINGTON, S.C. (AP) -- Regan Smith moved in front on a caution nine laps from the end and survived a green-white-checker finish to win the Southern 500 for his first Sprint Cup victory Saturday night.

Smith held off Carl Edwards the final two laps at Darlington Raceway in a race that turned ugly late when Kyle Busch tangled with Kevin Harvick and Clint Bowyer to set up the overtime finish.

After the race, Harvick tracked down Busch's car, stopped in front of Busch on pit road, then got out of his car and attempted to punch or grab Busch through his window. Busch then slammed into Harvick's driverless car, sending it crashing in the inside wall.

Harvick and Busch then stared down each other from their cars as they entered the garage before a standoff that looked as if it might erupt further. It finally ended when Busch bumped Harvick several times to make space to drive off. Both drivers were summoned to the NASCAR hauler.

Brad Keselowski finished third, pole-sitter Kasey Kahne was fourth and Ryan Newman fifth.

(Copyright 2011 by The Associated Press. All Rights Reserved.)