A Watford supporter is in a critical condition after being attacked in the street following Saturday’s match at Wolves.
West Midlands Police said the 44-year-old travelling fan was on his way from Molineux to Wolverhampton train station when he was assaulted and suffered a serious head injury.
The incident followed a 2-2 draw between the teams in the Championship. Wolves have expressed their "disgust" and along with Watford have shown concern for the injured man.
In a statement released on Sunday, West Midlands Police said: "Detectives have launched an investigation after a Hertfordshire man received life-threatening injuries in an unprovoked assault in Wolverhampton yesterday.
"The 44-year-old was with a group of friends making their way to the train station to return home to Hemel Hempstead just after 5pm when they were attacked in Littles Lane."
Detective Sergeant Adam Keen said: "The group of friends were completely outnumbered and the victim suffered a severe head injury which has left him in a critical condition in hospital.
"His family have been informed and we are in the process of taking statements from witnesses and locating any CCTV which might have captured those responsible for the attack."
Watford expressed shock over the incident, saying on the club’s website: "The thoughts of everyone associated with Watford FC are with a Hornets’ supporter – at yesterday’s game – who is now critically ill after an unprovoked post-match attack."
Wolves chief executive Jez Moxey said: "We are deeply saddened to hear of this incident and our thoughts go out to the supporter concerned and his family.
"As a club we deplore any violence in or around football matches, and we will work closely with the relevant authorities to help bring the perpetrator, or perpetrators, to justice.
"All right-minded football supporters will share in our disgust at this violent incident, and I would implore anyone with any information to contact the police."