LeAnn Rimes -- Guess What, Bitches? I CAN STILL SING [VIDEO]

With lawsuits and cat fights, it's easy to forget LeAnn Rimes is a powerhouse singer -- seriously, powerhouse -- so here's an awesome video of her KILLING IT at a Nashville bar recently.

The clip was shot inside Robert's Western World last month. Sources tell TMZ, Rimes showed up with her husband Eddie Cibrian, and some friends -- who unanimously encouraged her to get on stage.

Rimes reluctantly obliged, and the band struck up the country classic "I Fall to Pieces." The crowd went nuts, which makes sense ... because Rimes nailed it.