When Nunes faces Pena on Saturday, she will be defending the bantamweight title for the sixth time and making her eighth title defence overall.
Pena, 32, has repeatedly called out Nunes for a title shot throughout her career, and comes into the fight off a submission win over Sara McMann in January.
With two defeats in her past four fights however, the American has suggested, external Nunes may be under-estimating her – a claim the champion denies.
“Julianna has nothing to lose. I’m expecting everything, she’s going to be 100%,” says Nunes.
“I want to walk in and put a show on for the fans and Julianna is also that kind of fighter. It excites me to know that because those fighters are the ones I like. She’ll really show up.”
“My whole career, all my opponents say the same thing. Julianna’s just saying the same things that my other opponents have said – and I’ve already beaten them.
“I feel for sure in the best shape and everything is ready to go.”
If Nunes beats Pena, it will be her 15th victory, extending her record as the woman with the most wins in UFC history.
She is currently on a 12-fight winning streak and has not lost for seven years.
With victories over all her rivals in the featherweight and bantamweight divisions, Nunes has even called, external for the UFC to bring rivals in from other promotions to challenge her.
Some have also suggested the idea of a trilogy super-fight with Valentina Shevchenko, someone Nunes has already beaten twice.
However there are uncertainties over the fact it would require the women’s flyweight champion to move up in weight from a division she has dominated and looked her best in.
Whatever happens, Nunes is confident that her legacy is already secured.
“The best ever, I’m the greatest for sure,” says Nunes.
“Because I did everything, and everyone is going to remember that. When they hear my name, they remember I accomplished everything that a fighter would want to.
“Every single fighter – ask them what they want to do in MMA. You will hear my name, ‘what Amanda has done’.”