Carlos Ulberg won the UFC light heavyweight championship Saturday — and he did it on one good leg.

In one of the most improbable moments in recent UFC memory, Ulberg (14-1) dropped Jiří Procházka with a left hook in the first round of their 205-pound title fight at UFC 327 in Miami, just moments after suffering an apparent injury to his right knee. The injury occurred during an exchange on the feet, when Ulberg’s knee buckled as he took a step backward and slipped to the canvas.

Ulberg got to his feet but was visibly compromised and slipped again shortly after he threw a head kick. It looked like Ulberg was heading for a loss until he suddenly landed a perfect left hook that sent Procházka crashing to the canvas. Ulberg followed with shots on the ground to secure the sixth knockout of his career at the 3:45 mark.

UFC CEO Dana White said he did not have an update on Ulberg’s injury.

“I blew out my knee, but I never counted myself out,” Ulberg said. “I knew that all I needed was that one shot. I knew Jiri would come forward. I knew as soon as I landed the left hand, he was gone. I’ve got to sort this knee out, but I’m the champion.”

Procházka (32-6-1), a former champion who was looking to reclaim the belt he was forced to vacate in 2022, said he recognized Ulberg was injured and dropped his guard.

“I felt mercy in that fight,” Procházka said. “I felt sorry for him. This is one of the biggest lessons in my life. I can’t understand. That fight was won. I won that fight. I had it. It was in my hand. I just let him [back] because I saw his injury. F—. Life is about that. Learn and be better.”

Procházka appeared to immediately notice the injury and even pointed to the ground in front of Ulberg, almost gesturing that he would stand and trade in place with the New Zealander. Procházka landed several good leg kicks after the injury, all to Ulberg’s lead left leg. It looked like a nearly impossible scenario for Ulberg, and there appeared to be a chance doctors might stop the bout between rounds.

Ulberg, who trains out of the same City Kickboxing Gym as all-time middleweight great Israel Adesanya, remained composed. According to UFC Stats, he outlanded Procházka in the fight 21-11 and joined Alex Pereira and Muhammed Lawal as the only men to knock out Procházka.