Gone in 20 seconds! Francis Ngannou DESTROYS unbeaten Jairzinho Rozenstruik in super-quick fashion at UFC 249 (VIDEO)

Heavyweight contender Francis Ngannou was already frustrated not to have been given his second shot at the UFC heavyweight title, and he took that frustration out on undefeated former kickboxer Jairzinho Rozenstruik at UFC 249.

Ngannou had worked tirelessly with coach Eric Nicksick in isolation at Xtreme Couture in Las Vegas as he prepared to face Rozenstruik, who had called him out following his dramatic late KO of Alistair Overeem.

But, as the old phrase goes, be careful what you wish for.

Rozenstruik started out looking relaxed, and connected with a solid low leg kick as he looked to establish his kickboxing range early on. But that strike proved to be the only strike in anger he would land, as Ngannou exploded into life.

"The Predator" unleashed a powerful salvo of hooks tha forced Rozenstruik back against the fence, where he was caught flush by a massive left hook from the Cameroonian contender.

The shot knocked out "Bigi Boy" instantly, and needed referee Dan Miragliotta to dive in to spare him any further punishment as Ngannou waded in with more heavy shots.

It was one of the scariest, most devastating performances we've seen in the octagon in a long time, as Ngannou left no doubt about his status as the next best heavyweight on the planet after champion Stipe Miocic and former champ Daniel Cormier, who will do battle in a title rematch later this year.

Whoever wins will surely have to face Ngannou next, and line up to defend the title against the scariest fighter in the world.