Julianna Pena’s jiu-jitsu coach has said his fighter was underestimated by Amanda Nunes this month, following Pena’s submission victory over the Brazilian.

Pena defeated Nunes with a rear naked choke in the second round of the UFC 269 co-main event to win the women’s bantamweight title, much to the shock of many fans.

Nunes is widely considered the greatest women’s mixed martial artist of all time, but the 33-year-old – who still holds her featherweight title – underestimated Pena ahead of the bout, according to Luiz Claudio.

Claudio, long-time jiu-jitsu coach of Pena, told MMA Fighting: “I do think she underestimated her.

“Same thing [that happened with] Anderson [Silva]. I love Anderson, I respect him a lot, his style is to showboat. But unfortunately [Chris] Weidman touched his chin and we lost the fight.

“And I think that’s normal. [Nunes] had no one left to beat really. Who else was she supposed to beat? Julianna, and who else?”

Prior to her defeat by Pena, Nunes was unbeaten in seven years, having won 12 fights in a row.

Pena, meanwhile, entered the pair’s clash with two wins and two losses in her four previous outings.

“I don’t think Amanda underestimated her to a point of not training,” Claudio said. “I think she trained hard, she knew Julianna wasn’t easy.

“If we do have a rematch, she will obviously [be motivated]. We poked the ‘Lioness’. We’ll respect her, it’ll be tough. If this rematch happens, it’s the rematch of the century.”

Claudio also admitted to fearing that Pena would lose in the first round, when Nunes took the Venezuelan-American’s back.

“[Nunes] submits people from that position,” Claudio said. “I thought: ‘Please God, we may lose, but let’s at least put up a fight, five rounds.’”

Pena turned the tide in the second round, however, stunning Nunes on the feet before submitting her on the mat.

“When she took Amanda to the ground, I said: ‘We won the fight,’” Claudio said. “When she took her back, I knew she would catch her.”