A Millwall fan was taken to hospital after being assaulted close to St Andrew’s stadium on Saturday afternoon.
A 30-year-old man from Smethwick was arrested a short time after the assault which has left the 60-year-old Millwall fan seriously injured.
Police said the victim, from London, was with his family and had just arrived at the home of Birmingham City football club when he was assaulted on Cattell Road just before the 3pm kick off.
The motive for the attack is not yet known, West Midlands Police said.
A force spokesman said: “We’re working closely with both football clubs and are supporting the man’s family.
“We have spoken to witnesses, reviewed CCTV footage and have already forensically examined the area.
“The arrested man is being held on suspicion of a Section 18 assault.”
Benik Afobe scored a 96th-minute penalty to earn Millwall a crucial point in their push for the Championship play-offs.
