Fighter records fastest knockout in combat sports history as Conor McGregor responds to near-impossible feat

A fighter recorded the fastest knockout in combat sports history as Conor McGregor was left stunned by the near-impossible feat.

Bare Knuckle Fighting Championship returned on Friday as the promotion set up shop in Atlanta, Georgia.

In the main-event, Keith Richardson stopped Michael Larrimore in just 21 seconds of the first round while Derrick Findley edged out Joe Elmore by split decision in the co-main event.

But Justin Watson stole the show with his remarkable performance against Cole Ferrell in their undercard bout.

Incredibly, Watson vs. Ferrell lasted just TWO seconds as UFC star McGregor couldn't believe what he witnessed.

As soon as referee Bryan Miner stepped back to start the contest, Watson landed a devastating overhand right flush on his opponent's chin, immediately sending him to the shadow realms.

Miner wasted no time in waving off the fight as Watson registered what has to be the fastest knockout in combat sports history.

The crowd inside the Gas South Arena erupted as Ferrell briefly protested the knockout, but it was clear to see that he was in no shape to continue following the brutal strike.

His legs were unsteady as he rose to his feet, still feeling the effects of the stinging punch.

McGregor, who is part owner of the fledgling bare knuckle promotion, took to social media to celebrate the two-second knockout victory.

He reposted the clash between Watson and Ferrell on his Instagram story, accompanied with the caption: "The worlds [sic] fastest KO! WOW!"

BKFC president Dave Feldman added: "2.9 seconds, the fastest knockout in combat sports - unbelievable."

To make Watson's knockout even more impressive, he was actually the underdog heading into the fight so he also managed to pull off a considerable upset with the two-second victory that will be etched in BKFC history.