Police are investigating an alleged racist gesture by a fan during the Premier League match between Sunderland and West Brom last Saturday.
The incident occurred after Romelu Lukaku, who is black, put West Brom 3-1 up in their 4-2 victory.
"Police are carrying out inquiries after a report of racist abuse received at the Sunderland v West Brom match," said a Northumbria Police spokeswoman.
"A report was received at 2210 on Saturday, 24 November."
The man was pictured making an apparent "monkey" gesture.
A Sunderland spokesperson added: "SAFC operates a policy of zero tolerance towards racism and anti-social behaviour of any kind. Naturally we will co-operate with the police in fully investigating any such incidents."