UFC fighter stuns opponent with crazy final-second KO

Brian Ortega looked to be heading for defeat in his UFC 199 battle against Clay Guida until he produced a brutal flying knee with just seconds remaining.

Guida had dominated the fight but wasn't able to put Ortega away, but looked likely to pick up the win by decision.

With time expiring in the third and final round, Ortega knew he had to pounce and did so in stunning fashion.

The American fighter hit his opponent with an incredible knee to the face, sending his compatriot crashing to the canvas.

Guida was so dazed he tried to fight off the referee who had dived in to stop the fight.