The sole numbered event in September has undergone a significant change. While the headlining rematch between flyweight champion Joshua Van and former champion Alexandre Pantoja, along with the rest of the main card and preliminary bouts, is set, the co-main event at UFC 331 has undergone a major change.

The September 19 card was initially scheduled to feature a non-title bout between top-ranked lightweights Arman Tsarukyan and BMF champion Charles Oliveira. However, the UFC had to race for a replacement after Oliveira withdrew from the matchup. The former lightweight champion reportedly pulled out following the tragic death of his close friend and training partner Allan Nascimento, who passed away three days ago after suffering a heart attack.

“UPDATE: After Charles’ teammate and friend and UFC fighter Allan Nascimento passed away tragically this week, Charles Oliveira will be taking time off to grieve his friend and will not be fighting Arman Tsarukyan at UFC 331 anymore,” the Instagram post from Connected MMA read. “Hopefully Charles takes the correct time he needs. Praying for him and the Chute To Box family. 🙏🏼🙏🏼”

It was a crucial matchup for 36-year-old Oliveira. Yet, stepping away from such an opportunity to grieve the loss of a close friend shows what Nascimento meant to the former champion. For Oliveira, Allan Nascimento was more than just another teammate. He trained with Charles Oliveira, Elves Brener, and numerous other UFC fighters regularly at Diego Lima’s Chute Boxe Academy in São Paulo, Brazil. He also served as their trusted cornerman in many of their biggest fights. Even Oliveira cornered Nascimento for many of his UFC fights. This should explain why the untimely passing of Allan Nascimento, that too at only 34, has hit Oliveira so hard.

Following the knockout loss to Ilia Topuria in June last year, Charles Oliveira had gradually rebuilt his momentum, securing important wins against Mateusz Gamrot and Max Holloway, the latter earning him the BMF title. A victory over an established contender like Arman Tsarukyan would have moved him one step closer to another title shot. It would have also allowed him the opportunity to avenge his 2024 loss to Tsarukyan.

Instead, Oliveira chose to step away from that momentum, knowing he may once again have to work his way back into another marquee fight before earning another title opportunity. That decision, made so he could mourn a friend who is no longer with him, reflects the bond Oliveira shared with Nascimento.

A day after he paid his tribute to his friend, the BMF champion shared an emotional message on Instagram.

“Please just think about it for a while, because everything I said came from my heart. ♥️” the caption read.

“Today was Elanjito’s funeral, and I spent a lot of time thinking during the service and on the drive home,” he said in his native Portuguese. “I wanted to tell you something: we already live in a messed-up world where people do terrible things… But that’s not what I want to focus on. I want to tell you this: don’t stop hugging the people you love, and don’t let a stupid argument come between you and the good people in your life, because tomorrow it might be too late to give them a hug.

“Elanjito was one of the purest people I’ve ever known—a real man, respectful, and one of the most disciplined people I’ve ever met. He went home, went to sleep, and the next day, he never woke up. That really hits hard. I just wanted to tell you this: don’t leave for tomorrow what you can do today. One of our brothers has passed away, but now we have something even greater to carry with us….”

More than a teammate: Allan Nascimento’s lasting impact on Charles Oliveira

34-year-old Allan Nascimento was reportedly found unresponsive on Monday morning. Reports suggested he passed after suffering a heart attack in his sleep.

According to the UFC’s official statement, a medical team attempted to resuscitate him, but to no avail. Nascimento was later pronounced dead. As news of his passing spread, an outpouring of condolences followed, with many expressing their love and support for the late fighter’s family, including his wife and children.

Nascimento began his professional journey in 2011, competing primarily on the São Paulo regional circuit. He suffered a major setback when his first attempt to reach the UFC ended after Raulian Paiva defeated him in a closely contested duel.

It took another three years before Nascimento finally made his UFC debut, which also ended in a split decision defeat.

However, the Brazilian rebounded with a four-fight winning streak before Mitch Raposo snapped it with a split decision at UFC Vegas 119 (Kape vs. Horiguchi).

A former Predator FC bantamweight champion, Nascimento was never stopped in a professional fight, highlighting both his durability and his toughness inside the cage.

Understandably, his absence is expected to have a significant effect on Oliveira and the rest of the Chute Boxe team.

A similar tragedy unfolded in boxing when former heavyweight champion Anthony Joshua lost two of his close friends and team members, Sina Ghami and Latif Ayodele, in a road accident. It took nearly six months before Joshua returned to action while continuing to deal with that personal loss.

Given his closeness with Nascimento, Oliveira may also take some time away before he is mentally and emotionally ready to resume training and decide his next move.

In the meantime, the promotion has found a replacement in fellow Brazilian Mauricio Ruffy, who is coming off a sensational win over Michael Chandler on the White House card, to face Tsarukyan.