11:45 AM PT -- The woman who reported the incident to cops was standing next to the drink thrower -- but she claims the mic hit her too. Some video angles seem to show the mic hitting her after it ricocheted off the other fan.
Cardi B might not get away scot-free with that microphone toss in Las Vegas -- she's now listed as the suspect in a battery ... TMZ has learned.
The woman who was struck by Cardi's mic when she hurled it into the crowd at Drai's Nightclub on Saturday ... went to Las Vegas Metro PD the next day to report the incident.
Twitter, TikTok / @j_blizzyy
She told police she'd been struck by an item -- the microphone -- thrown from the stage. Of course, the whole incident was captured on cameras during Cardi's show.
As we reported, a woman in the crowd threw some kinda liquid at Cardi while she was performing ... and the rapper snapped, immediately throwing the mic in retaliation.
The mic struck the drink thrower, but ricocheted and also hit another woman standing next to her ... as seen in the footage.
Prior to the altercation, Cardi and her DJ had implored the crowd to splash water on her to cool her off in the triple-digit weather -- but obviously, she didn't take kindly to whatever the woman threw later in the show.