Boxer claims most brutal knockout of the year

American fighter Justin DeLoach has captured one of the most coveted titles in all of boxing – the most brutal knockout of the year.

Footage of the jaw-rattling blow quickly went viral after the 22-year-old orthodox boxer floored rival Dillon Cook in their Showtime Super Welterweight fight on Friday (US time).

The two combatants were in the fourth round of their eight-round bout when Dillon was left reeling after a strong combination from DeLoach.

However, the 25-year-old Cook refused to be backed into the corner and tried to strike back with a powerful left.

But despite hitting the target, the strategy left him exposed and DeLoach took full advantage, connecting with a powerful right hand to the jaw of Cook.

The blow sent Cook to his knees as he slumped over with head bowed in defeat.

The referee gave him the count but a valiant, last ditch attempt to get back to his feet could not save a woozy Cook.

"I’m happy with my performance," DeLoach told USA Today after the fight.

"Dillon was a good fighter who moved a lot. I know I have to do better cutting off the ring.

"He landed with a left a second before I landed that big right. This was a great win for all of us. I’m ready to do this again.’"

The win improved DeLoach's record to 14-1, while Cook fell to his first career from seventeen fights.