Julianna Peña Says Amanda Nunes Is Not Taking Her Seriously

Julianna Peña is less than a week away from the biggest fight of her life against Amanda Nunes ... and the "Venezuelan Vixen" has a message for the doubters, telling TMZ Sports she isn't satisfied just being here -- she's gunning to win.

"I feel like a lot of people are sleeping on me and they think I'm a sacrificial lamb but I definitely think that, you know, I know that I'm definitely not a sacrificial lamb and everyone loves an underdog," Peña told us.

32-year-old Peña is the #3 ranked bantamweight in the UFC -- and has been all but demanding a title shot with the 33-year-old champ, Nunes -- because she truly believes she will get the W when they fight at UFC 269.

"I'm ready. I am in the zone. I have never felt more physically or mentally prepared in my life and it's my time. It just feels so great to know that I have literally left no stone unturned. I'm ready to go. I'm in the zone!"

Peña's been with the UFC since 2013 ... and has a professional record of 10-4. She's beaten some badass women like Jessica Eye and Cat Zingano.

Despite the impressive resume, Julianna's a big underdog against Amanda. In fact, bettors have to wager about $900 just to win $100 on Nunes.

And, it's not just the oddsmakers who doubt Peña can win ... 'cause Julianna told us she feels Amanda isn't taking her seriously.

"[Nunes] called me delusional. She said that I'm reckless. I don't think that she's taking me seriously at all and you know, that's fine."