Jeff Gordon is a four-time NASCAR Sprint Cup champion. Tony Stewart is a two-time champion.
They both have a place among the greats in the sport's history and both undoubtedly will find their way into the NASCAR Hall of Fame.
Both Gordon and Stewart have more than just their other competitors chasing them, though.
Time may be their most powerful pursuer.
Both Gordon and Stewart turn 40 this season and they have watched for the last five years as Jimmie Johnson has pushed both of them to the shadows en route to Johnson's unprecedented dominance.
Here's a look at some factors that could impact whether one of them could return to the top of the Sprint Cup mountain in 2011.