Kayla Harrison is still itching for a fight with Amanda Nunes ... telling TMZ Sports if the UFC's G.O.A.T. ever comes out of retirement, she wants to throw hands with her badly!!!
But, don't get it twisted ... there's absolutely no bad blood on Harrison's end toward Nunes -- she just wants the scrap to prove that she can beat the best ever.
"She is the greatest of all time," Harrison said of The Lioness. "She was the woman. And I wanted to be the woman.