DARLINGTON, S.C. — Brad Keselowski provided perhaps the biggest throwback at the Southern 500 — giving Team Penske its first victory at Darlington Raceway in 43 years.

“This is probably the biggest win of my career,” said Keselowski, the 2012 NASCAR champion.

Keselowski beat leader Kyle Larson out of the pits — “It couldn’t have been more than 10 feet,” Keselowski said — with 22 laps to go, then pulled away on the restart to sweep the weekend at Darlington.

Keselowski took the Xfinity race Saturday when leaders Ross Chastain and Kevin Harvick wrecked late. This time, Keselowski and his crew took advantage on the final caution to move in front with a fast pit stop.

Keselowski then did the rest as he opened a 1 1/2-second lead down the stretch.

It was Keselowski’s first victory of the season — the 25th of his career — and the first time a Team Penske driver has won at Darlington since Bobby Allison in the 1975 Southern 500.