Tommy Robinson appears to send an England football fan crashing to the ground with a sickening punch outside last night's England game in Portugal.
Footage obtained by The Mirror shows the far-right extremist in Guimaraes, Portugal, for the Nations League semi-final with several of his supporters.
The failed MEP candidate for the north west can be seen wearing a camouflage jacket and striding among fans.
In the video, one man puts his arm around Robinson before raising his fist to the air.
As an inaudible exchange between two groups appears to intensify, the 36-year-old walks towards a fan and lands a blow to his face.
The man punched by Robinson can be seen lying on the ground wearing an England away shirt, struggling to get up as his pals come to his aid.
Another man approaches Robinson and says: "There's no need for that, is there?"
A voice, thought to be Robinson's, responds: "You'll get knocked out again bruv."
After a pause of a few seconds, a man says: "F*** about again, you'll get knocked out again bruv."
Other supporters can be heard shouting: "Go on Tommy lad."
Some people can then be heard asking for a picture with Robinson.
On Wednesday Robinson, real name Stephen Yaxley-Lennon, said in a selfie video he was in Portugal for the game.
Wearing the same jacket as the video, Robinson winks at the camera and says: "I'm in Portugal...at the game, no football banning order here mate."
In another video on social media, published on Wednesday, Robinson is in Stansted Airport, again wearing the same jacket, when a bystander approaches him and asks if he knows where the prayer room is.
The build-up to Thursday's Nations League semi-final against Holland was dominated by fan behaviour after two nights of disruption in Porto and some unseemly behaviour in Guimaraes.
The Football Association said it was working with the UK Football Policing Unit after trouble flared up in Porto on Tuesday and Wednesday, with the governing body saying those causing issues were an "embarrassment".
England manager Gareth Southgate used the same word to describe the group of troublemakers after Portugal bore witness to this latest reprehensible chapter.
"I haven't seen it, but I'm aware of it," the England manager said after his side's 3-1 extra-time loss to the Dutch.
"The saddest thing for me is that we have thousands upon thousands of fans who come here and support us brilliantly and have the ability to enjoy themselves without causing offence to anybody else and without creating any problems.
"And then we have a group who are an embarrassment.
"As an Englishman, they're not supporters of the team. They reflect so poorly on us as a country and we don't associate ourselves with them at all."
The FA recently launched a video called 'Don't Be That Idiot', highlighting the embarrassment unacceptable behaviour can cause - a call that appears to have fallen on deaf ears.
Press Association Sport has seen the FA's message to England Supporters Travel Club members on their Facebook group, warning they will "investigate incidences of inappropriate behaviour before, during or after" the game.
The governing body highlighted that the "overwhelming majority" are acting appropriately and following the Three Lions the "right way", just as Deputy Chief Constable Roberts did.
"It is fairly depressing really," he said.
"It is something we have become used to. I think we hoped after the Russia World Cup, where everything worked well in terms of fan behaviour, that we might have turned the corner.
"But we have seen a few games since then where we have seen this loutish, drunken behaviour return, and unfortunately now, we have had a couple of nights of it in Porto.
"It is a real shame because there are a lot of England fans here who will behave themselves but it is always this drunken minority who behave in a yobbish way who make the headlines."
