Olympian Kayla Harrison Challenges Cris Cyborg, I Ain't Afraid Of You

If Cris Cyborg beats up Amanda Nunes ... there's a bad ass 2-time Olympic gold medalist who wants a piece of her ... and she ain't after a participation trophy.

Kayla Harrison -- who won gold in judo in London (2012) and Rio (2016) -- and is 2 and 0 in MMA ... told TMZ Sports she has her sights set on the most feared female fighter on the planet ... Cyborg.

"I want to be the best, and right now Cris Cyborg is considered the best probably pound for pound female ever."

Now, Kayla ain't saying she's ready for Cris -- who has 20 wins and only 1 loss -- just yet ... but she does have her eye set on the legendary champ ... and is determined to step in the cage with Cyborg.