Aussie MMA fighter KO'd by cheap shot head kick

MMA battles are renowned for brutal blows on floored fighters and Australian combatant Rob Lisita has finished on the receiving end of one of the worst cheap shots ever.

Lisita lasted just six seconds before being sent to the canvas by Russian rival Timofey Nastyukhin in a featherweight bout at ONE Championship 43 in Thailand.

The rapid fire assault sent the 33-year-old asleep before he hit the ground.

But as is the case in the sport, Nastyukhin didn't stop there with the Russian walking around his prone rival and then delivering a savage football-style kick to the Aussie's head.

Footage of the blow makes for sickening viewing as Lisita's arms fly up in an involuntary action before the referee rushes in to push away Nastyukhin.

Medical officials then race to Lisita's aid.

The savage attack was denounced by MMA website Bloody Elbow, with writer Mookie Alexander describing it as an act of "pure violence".

Alexander revealed that Nastyukhin had used a football kick as the finishing move in each of his four previous victories in the ONE Championship.

Such kicks are illegal in the UFC and many other promotions because they’re considered too dangerous, but are still allowed in some leagues.