The BlueTeam and the RedTeam

From Roman Sports and Spectacles, by Anne Mahoney:

Yet Roman chariot racing came as close to anything in the ancient world to the team sports we know today. Each chariot belonged to one of four "factions" or colors, called Blue, Green, Red, and White. ... Spectators were loyal to their colors, and might identify themselves as Blues or Greens depending on what team they rooted for. Literary sources tell us the Romans often seemed to care more about the color or team than about the merits of the individual drivers. But whereas teams in modern American sports generally represent a city or a school, the four chariot factions never stood for anything other than themselves.

Oh, but what a spectacle.