KFC’s switch to Coke is the latest sign of a decades-long slide, and PepsiCo’s CEO says fixing soda is now a priority.

KFC said last week that Coca-Cola products would begin replacing PepsiCo drinks at KFC's 3,700 U.S. restaurants in January.

As sports drinks and water own performance occasions, Coca-Cola and PepsiCo are increasingly using soda partnerships to tap into fandom and the broader sports zeitgeist.

Former PepsiCo-owned chain switched sides after a secret showdown, replete with taste tests and discussions over strategy.