UFC fighter Felice Herrig is giving TMZ Sports a blow-by-blow of her bloody Vegas street fight ... and she tells us the whole thing started over a penny.
35-year-old Herrig --the #12 ranked strawweight -- was in Sin City for UFC 246 ... when her night out on the town started to resemble her day job.
“I was just like, ‘Dude it’s just a penny,’” Herrig told us. “And then I thought it was over and I was walking out with my friend , Kim, and she comes up from behind me and she was like, ‘It was on heads!