Pop Rivalry: Aguilera Endorses Coke

March 28 -- First Pepsi and now Coke have lined up pop stars to represent them, but they're as different as, er, Coke and Pepsi.

The BBC reports that pop singer Christina Aguilera has inked a sponsorship deal with soft drink giant Coca-Cola — a mere six weeks after rival star and fellow Mickey Mouse Club alumna Britney Spears signed a similar deal with Pepsi.

Aguilera, 20, is reportedly still working out the deal with Coca-Cola, which she will promote in South America and the United States, where she's achieved her greatest fame.

Spears, 19, signed what Pepsi called the biggest entertainment deal in company history when she agreed to hawk the soda throughout the world. Her first commercial for Pepsi, which also featured former Sen. Bob Dole, aired Sunday night during the broadcast of the Academy Awards on ABC.

After their years on the Mickey Mouse Club, both singers pursued recording contracts. Spears broke through in late 1998 with the single "… Baby One More Time." Aguilera's self-titled debut album came eight month's after Spears' first recording, in August 1999, and was greeted with similar success.

The two squared off for the prize of Best New Artist at the February 2000 Grammy Awards — and Aguilera came home with the trophy. Spears, however, remains the queen of album sales, with last year's Oops! … I Did It Again selling more in its first week than any other recording by a female artist.