Both Tony Stewart and Jimmie Johnson began their respective special weekends on Friday at Homestead-Miami Speedway.
After 18 seasons, Stewart will call it a career after Sunday's FordEcoBoost 400 in South Florida.
Johnson will battle for a seventh NASCAR Sprint Cup Series championship with Carl Edwards, Joey Logano and Kyle Busch in the Championship Round of the Chase on Sunday. If he wins it all, he'll tie legends Richard Petty and Dale Earnhardt.
And each driver is sporting remarkably-designed helmets to commemorate the occasions.