Shocking footage posted to social media shows two blokes going at it in the train carriage while other passengers look on.
The incident occurred on the London Underground Victoria Line at around 10:30pm on Wednesday.
Several others on the train can been attempting to split the pair up as the train whizzes through London.
Other horrified travellers move seats and change carriages in an attempt escape from the brawl while the men hurl insults at one another and throw punches.
One of the men appears to knee a peacemaker – thought to be his own brother – in the face before shouting: “You aren’t staying at mine”.
The video was posted to Twitter shortly after Chelsea handed out a 4-1 stuffing to London rivals Arsenal in the Europa League final in Baku, Azerbaijan.
“It continued until the next stop then one guy jumped off. They 100% knew each other”
Connor Humm, who recorded the footage, said it was unclear what sparked the brawl but he believed Arsenal’s poor showing in the match may have been a factor.
He told Mirror Online: “Me and my friend had left the bar at Highbury and Islington station and jumped on the Victoria line after Arsenal had lost.
“Next thing we knew there were a group of guys getting irate and louder having an argument.
“It wasn’t clear what it was about but one can only assume it was about the game because, let’s face it, everyone was very upset.”
Humm, also an Arsenal fan, added: “The two men seemingly wanted to fight each other. One man’s younger brother then jumped in and his brother then turned on him and kneed him in the face.
“It continued until the next stop then one guy jumped off. They 100% knew each other.
“One of the men shouted at the other telling him ‘you aren’t staying at mine’, along them lines.”
The shouting and taunts continue once they are separated while friends try to calm things down as the train approached King’s Cross St. Pancras station.
One man calls the other a “p***k” and one shouts about taking his “f***ing head off”.
One of the men screams “you and your brother let’s go, now that the Tube is empty let’s f***ing go” as passengers leave the train.
There is another scuffle but the men are separated again as one accuses the other of throwing a punch, calling him a lying “c**t”.
Mr Humm tweeted afterwards: “Just come out the tube. Two Arsenal fans trying to kick the sh*t into each other.”
He added: “His brother holds him off then his brother decides to knee his own brother in the face.”
Fellow Twitter users called the fight “embarrassing” and described those involved “animals”.
One wrote: “From The Invincibles to the Imbeciles.”
A spokesperson for British Transport Police said: “British Transport Police is aware of a video on social media which shows a fight on board a Victoria Line train.
“Officers are now making enquiries, anyone with information should contact BTP by sending a text to 61016 or by calling 0800 40 50 40 quoting reference 213 of 30/05/2019.”