Everyone wants to know what happened to Raoni Barcelos.

Unfortunately, there still is no definitive answer.

The 39-year-old Ultimate Fighting Championship (UFC) veteran was involved in a terrifying scene during the fifth round of his UFC Vegas 121 main event against Raul Rosas Jr. last night (Sat., Sept. 26, 2026) inside Meta Apex in Las Vegas, Nevada.

Barcelos suddenly collapsed near the fence and was unresponsive as medical personnel rushed into the Octagon (watch it). He was eventually transported to a local hospital, where he was reportedly awake and conscious.

Exactly what caused the frightening incident remains unclear.

Dr. Brian Sutterer, MD, offered several possible explanations on his YouTube channel shortly after the fight. Sutterer is a board-certified sports medicine and physical medicine and rehabilitation physician who completed his residency and sports medicine fellowship at the Mayo Clinic. He has also built a large online following by breaking down high-profile sports injuries in easy-to-understand terms.

However, it is extremely important to stress that Sutterer did not examine Barcelos and does not have access to his medical records or imaging. His analysis was based entirely on publicly available footage.

In other words, this was not a diagnosis. It was an explanation of what doctors may investigate following such a frightening and unusual collapse.

Why it wasn’t a knockout

Sutterer cautioned against immediately assuming Barcelos suffered a traditional knockout.

“I think if you say unconscious athlete, the immediate assumption is that this was a knockout, this was a concussion, a brain injury,” Sutterer explained. “When in reality, here you have a collapsed athlete, a downed athlete, that may be from something like a traumatic brain injury, but can also be from cardiac things or otherwise.”

There was no obvious knockout blow immediately before Barcelos collapsed.

Barcelos was standing against the fence when Rosas dragged him toward the canvas. His head appeared to make slight contact with the cage during the sequence, but Sutterer said he would be “extremely surprised” if that relatively minor impact alone caused what followed.

What doctors could investigate

Sutterer identified severe exhaustion, dehydration and electrolyte abnormalities as possible causes after nearly 22 minutes of a grueling mixed martial arts (MMA) fight.

He also discussed the significant damage around Barcelos’ left eye. In rare circumstances, increased pressure around the eye can trigger a syncopal response and cause someone to pass out.

“This is something just like crazy sheer exhaustion, electrolyte abnormalities, dehydration, or even something like buildup of intraocular pressure in the eye that caused a syncopal response,” Sutterer said while outlining the more optimistic possibilities.

There was also at least one encouraging sign during the immediate medical response.

Sutterer noticed a ringside physician quickly checking Barcelos’ carotid pulse. Medical personnel did not begin cardiopulmonary resuscitation (CPR) or use a defibrillator before removing Barcelos from the cage, which would suggest he had a pulse and was not experiencing cardiac arrest at that moment.

However, doctors would also need to rule out a much more serious possibility.

Because Barcelos had just endured a lengthy fight involving repeated blows to the head, Sutterer explained that medical personnel would have to consider a structural traumatic brain injury, including intracranial bleeding.

Unlike a typical concussion, a brain bleed can worsen over time as blood accumulates and pressure increases inside the skull. That is why obtaining a CT scan as quickly as possible would be an important part of evaluating this type of collapse.

Again, there is currently no indication that Barcelos suffered a brain bleed—or any of the other conditions Sutterer discussed. These were simply potential explanations that medical personnel would investigate and rule out.

Until Barcelos, his team, UFC or his doctors release additional information, anything beyond the available updates would be speculation.

For now, the most important news remains the encouraging news: Barcelos is reportedly awake and conscious after being transported to the hospital.

After the horrifying scene that unfolded inside the Apex, that is about the best update anyone could ask for while waiting to learn what actually happened.

For complete UFC Vegas 121 results, coverage, and highlights click HERE.