Paige VanZant won't let a massive bloody wound keep her from fighting -- she's already stitched up the gash on her foot and got back on her grind. 

The UFC superstar opened up a gnarly hole in her foot on Wednesday -- but one day later, she was back working out ... hitting a set of crunches with a fresh set of stitches.

VanZant is rumored to fight Jessica Eye at UFC 216 in October -- and at this point, it doesn't appear she's gonna let the injury keep her out of the Octagon.