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Julianna Pena believes she has an even better read on Amanda Nunes after spending time with her past and future opponent on The Ultimate Fighter. Pena pulled off a shocking upset at UFC 269 in December, cashing as a major underdog to defeat the all-time great for the UFC women's bantamweight champion.

The reality TV show has produced some nasty mind games between its rival coaches at times. Pena believes she already has the mental edge over Nunes and so did not feel compelled to gain ground on the reality show.

"I think I've always had the mental edge when it comes to Amanda. I've been calling out this fight for the last five years," Pena told "Morning Kombat" this week. "She hasn't wanted to fight me. She's always made every excuse. Like me not making myself worth for her or 'I'm going to find Ronda instead' or finding a way to get out of every fight that we have. Obviously, what I feel and what I say and how I approach things bothers her. She has made that very clear."

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Pena did learn something about the woman deemed by many as the greatest of all-time in women's mixed martial arts.

"She's a little bit more high maintenance than I had originally thought. You'll see what I mean but that's all I can say for now," Pena said. "I really thought that I was high maintenance, like the most high maintenance, like no one gets more high maintenance than me. Right? I'm a diva! Then I experienced the things that Amanda was doing."

Pena cemented one of the greatest underdog victories in MMA history by defeating Nunes by submission. Looking ahead to their eventual rematch, the champion is prepared for her challenger to take things seriously.

"I think I lit a gas can of fire right underneath her behind. She is going to be more focused than she has ever been. I think she is going to be the best Amanda that she's ever been, which is funny because that is what she said she is going to do the first time," Pena said. "This time she is coming at 110%. I'm going to get the best version of Amanda Nunes. That's great because I was ready for that best version of Amanda Nunes in August. I was ready for that best version of Amanda Nunes in December. Whenever that date happens, hopefully in September on that Jon Jones card, I will be ready for that best version of Amanda Nunes."

Pena does not appear quite comfortable usurping the title of G.O.A.T. from Nunes at this stage. She pitched a more appropriate title that speaks to what she has accomplished thus far.

"Do you think that when you beat the G.O.A.T., you become the G.O.A.T. slayer?" Pena asked. "Well, then I think I might be the G.O.A.T. slayer."