Khabib Nurmagomedov scored an incredible victory in what many considered the biggest fight in the history of mixed martial arts, and then immediately marred what should have been his crowning moment.

The UFC lightweight champion Nurmagomedov finished the sport’s biggest star, Conor McGregor, retaining his belt via submission at 3:03 of the fourth round of his UFC 229 main event on Saturday night at T-Mobile Arena in Las Vegas.

But a wild scene broke out after the fight, in which Nurmagomedov jumped out of the cage and attacked McGregor teammate Dillon Danis. In the ensuing madness, one of Nurmagomedov’s teammates punched McGregor inside the cage.

Things came dangerously close to getting completely out of contol. After security finally managed to get a lid on things, UFC president Dana White refused to put the belt on Nurmagomedov, citing safety concerns.

The performance marred what was unquestionably the finest performance in the career of one of the greatest fighters MMA has ever seen. The now 27-0 Dagestan native entered the bout the winner all 10 of his previous UFC fights. The big question heading into the bout was how his style, in which he essentially mauls his opponents like an angry mama bear protecting her cubs, would fare against McGregor’s striking.

Nurmagomedov dictated the pace from the get-go. He took McGregor down early, and although he didn’t do much with his advantage, he stayed atop McGregor for the rest of the round and wore him down.

In the second round, though, he did a tremendous amount of damage to the former UFC lightweight and featherweight champ. Nurmagomedov dropped McGregor with a right, and soon thereafter took McGregor to the mat and then unleashed a ruthless assault in what was likely a 10-8 round. McGregor, however, weathered the storm, partially through questionable moves like fence grabs and an illegal knee to the head, and got back to his feet before the round was out.

By the third, it appeared that Nurmagomedov was starting to slow down. And McGregor, although tired, picked up the pace, landing with his left hand, and counter rights, to the head and the body, as well as kicks to maintain distance, McGregor likely won the third round.

But Nurmagomedov, who never sat on his stool between rounds, got back into gear in the fourth, and this time he got the job done. McGregor tapped to a rear-naked choke, making all four of his career MMA losses come by way of submission.

There were no postfight interviews after the Octagon following all the madness.

Nurmagomedov earned his ninth career submission victory and his 17th win via finish overall. McGregor, who was fighting in an MMA bout for the first time since his Nov. 2016 win over Eddie Alvarez, dropped to 21-4 and had a two-fight win streak snapped.