The year's biggest, most glamorous football game is today, featuring the two most popular athletes on Earth.

And no, it has nothing to do with Tim Tebow.

Rather, the two titans of Spanish soccer, Barcelona and Real Madrid, will meet, led by their respective mega-stars, Lionel Messi and Cristiano Ronaldo, to renew a rivalry so rich in history and glamor that it is known globally simply as El Clasico.

If you aren't aware of El Clasico, here's four reasons why you soon will be: