Petr Yan looked to be on his way to defending his bantamweight title for the first time at UFC 259 before an illegal knee turned everything on its head.

The first of three title fights on a monster card in Las Vegas was called off in the fourth round after Aljamain Sterling, a downed fighter, ate a knee from the champion.

Yan appeared to be in control after withstanding an early barrage from the challenger, and was working over Sterling, before it all came crashing down. Yan’s title was ripped from him as a knee landed on his downed opponent was deemed an intentional illegal strike.

“You can’t get more illegal than that,” Joe Rogan said in commentary.