Watch: Colby Covington's shocked expression after Kamaru Usman got knocked out cold by Leon Edwards

No.1-ranked welterweight contender Colby Covington was as surprised as anyone when Leon Edwards knocked Kamaru Usman unconscious with a stunning head kick at UFC 278 in Salt Lake City.

Catch Colby Covington's reaction to Edwards' KO of Usman below:

Covington was involved in two title bouts with Usman over the years and is widely regarded as the second-best UFC welterweight even after coming up short in both those fights. 'Chaos' has also stated previously that he's the only fighter in the division who could ever beat the now-former champion. So it's not surprising that the outcome of Usman's latest fight came as a shock to the former title challenger.

Edwards became the second British champion in UFC history after Michael Bisping when he dethroned the formidable Usman with a picture-perfect finish.

'The Nigerian Nightmare' was handed his first defeat under the promotional banner in his latest outing on Saturday. Usman was riding a 19-fight win streak into the fight and was also a huge betting favorite in this matchup.

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Dana White lauds Kamaru Usman for his performace at UFC 278

Kamaru Usman looked dominant for most of the fight and was well on his way to a decision victory through his relentless wrestling pressure. It was only towards the end of the final round that he was caught by a devastating kick that seemingly came out of nowhere.

Speaking to the media at the UFC 278 post-fight press conference, UFC president Dana White acknowledged that he was impressed by Usman's performance:

"I thought that Usman fought the perfect fight. You think of everything that was on the line for Usman tonight. Usman fought with absolute and total confidence all night. It might not be the most fan-friendly style but he was landing big shots to the body, big shots to the head, and elbows. He couldn't have fought a more perfect fight until the last minute."

Watch Dana White interact with the media at the UFC 278 post-fight presser below:

The loss brought an end to Kamaru Usman's astonishing reign as the 170-pound champion. 'The Nigerian Nightmare' was hoping to make a sixth successful title defense since capturing the belt from Tyron Woodley in early 2019.

With a win on Saturday, the 35-year-old would have tied former UFC 185-pound champion Anderson Silva's record for the longest win streak (16 fights) in the promotion's history.