Fan is knocked out by a single punch ahead of West Ham vs Chelsea

Brutal footage of a fan being knocked out outside the London Stadium ahead of West Ham's draw with Chelsea has gone viral.

The spoils were shared in the early kick-off after Emerson Palmieri scored the equaliser against his old club, cancelling out Joao Felix's first strike for Chelsea in the first half.

But there were ugly scenes prior to the fixture as supporters were involved in an altercation outside the ground.

Stewards tried to stop the fracas from escalating as both sets of fans came to face and goaded one another.

One in particular, wearing a black jacket and appearing to be a Chelsea fan, was doing a fair bit of taunting during a verbal altercation.

But out of nowhere it turned violent as the video shows a man landing a vicious punch that connected flush and knocked the other individual out cold in front of a frenzied crowd.

He lay motionless on the ground as two other men attended to him, with one appearing to pick up his ticket.

He was then placed in the recovery position by two nearby security employees after the sickening single punch to the head.

The man who had thrown the punch appeared to flee quickly, although there were multiple angles of the fight shared online to millions of people and his face was clear throughout.

And later on, another clip doing the rounds on social media showed the victim being pushed in a wheelchair, with blood pouring from his mouth.

Away Day Bible

Chelsea defender Reece James took to Instagram to condemn the scenes and stressed that "violence is not the answer".

"The news has crossed my attention that a fan was punched & knocked out before today's game," James wrote.

"I totally understand rivalry and the tension between teams in big games but violence is no answer. I hope he’s okay: Appreciate the traveling fans as always. Stick with us and stay safe. See u in Dortmund."

SPORTbible has reached out to the Metropolitan Police for comment.