Petr Yan's horrific loss against Aljamain Sterling and Adriano Moares' emphatic win over Demetrious Johnson shows two emotions for the same move in a sport called mixed martial arts.
Knee to downed opponent is illegal in UFC
Adriano Moraes Becomes the First Fighter to Get a Knockout Win Over Demetrious Johnson
Moraes executed a brilliant kick to send Johnson back to the ground after he tried to grab his single le in order to breath and recover.
Knee to a downed opponent is legal in ONE Championship.
Knees should be illegal in MMA
There's nothing wrong in having a situation where a fighter cannot hit another fighter in a sport where a fighter ends up landing hammer punches to an unconscious body after knocking him out. Knee to the head, to the nose can create permanent damage, and as much as these fighters are putting their life into learning this art, they shouldn't be forced to be so vulnerable to something as dangerous as getting hit by the knee while you are down.