Britney Spears BSPEARSADNAN011008_01.jpg TMZ is reporting that Britney must show up in court and face the judge on Monday - if she doesn't show or isn't completely cooperative, her custody case could be done once and for all!

Worse, the hearing promises to be ugly - TMZ hints at testimony from "LAPD, firefighters and paramedics" who responded to Britney's emergency. "We're told they're not going to paint a pretty picture," the site reports.

And if things don't go Brit's way? Well, she won't be able to rely on any help from the Sheriffs - they told TMZ that "they'll be there to 'handle' the situation"!

Sounds like a real high-noon showdown - Monday should be insane!