Britney Spears -- Beach Football ... Guess That Ankle Is Okay! (PHOTO)

Britney Spears' bum ankle kept her from performing Friday and Saturday night in Las Vegas, but it didn't keep her from playing beach football on Sunday!

Brit ditched the soft cast she had on her left ankle on Friday -- and hit the sand in Malibu to toss around the ol' pigskin with bf Charlie Ebersol.

After rolling her ankle Wednesday night, Brit cancelled her weekend shows, per doctor's orders.

Just a guess, but beach football probably was NOT what the doc ordered.