Not even divorce can keep Britney Spears and Kevin Federline apart ... at least at their kids' soccer game ... where the famous ex-couple joined forces this weekend to cheer their faces off.

Brit and K-Fed got together yesterday in L.A. to support their sons Sean Preston and Jayden James while the boys played soccer ... and everyone had a blast (laughing and smiling ... and not a single lawyer).

K-Fed's girlfriend Victoria Prince was also there, and it wasn't awkward at all. We're not even joking. Britney even played with Kevin and Victoria's new daughter Jordan Kay. How 'bout them apples.

One big happy family.