What exactly happened to Sean O’Malley’s leg at UFC 252 is still a little unclear.
Sometime around the middle of round 1, Chito Vera landed what seemed to be a slapping low kick to the outside of Sean O’Malley’s right leg. O’Malley immediately switched stances after the kick landed. After faltering and rolling his ankle on a move shortly afterward, he showed clear signs of being unable to put any weight down on the limb at all.
A few moments later and he was crashing to the canvas, unable to maintain his balance and create effective offense at the same time.