Chastain played the role of spoiler on Sunday, battling hard and aggravating Blaney to the point where contact was made in the battle up front.
After a brief three-wide battle on a late-race restart, he then set sail, becoming the first driver not part of the Championship 4 to win the finale since the current format’s introduction in 2014.
Behind him, the battle raged for the championship. Blaney ran down Kyle Larson and the two drivers had several close moments while fighting for control of the championship lead.
Blaney eventually cleared him and drove off, earning his first-ever NASCAR Cup Series championship.
It’s back-to-back Cup titles for Team Penske and a Ford sweep of all three national titles this year. Stewart-Haas Racing’s Cole Custer earned the Xfinity crown on Saturday and ThorSport Racing’s Ben Rhodes claimed the Truck crown on Friday.
Larson will end the year second in the final standings, William Byron third, and Christopher Bell fourth after a blown brake rotor ended his day early.