A man suspected of racially abusing West Bromwich Albion striker Romelu Lukaku during the match between Sunderland and West Brom has been released on bail.
Liam Jones was interviewed by police in Sunderland after a photograph showed him making what appeared to be a monkey gesture towards the on-loan Chelsea forward following his goal in the visitors' 4-2 win at the Stadium of Light last weekend.
Police confirmed that a 21-year-old man was on police bail after being held on suspicion of racially aggravated intentional harassment.
Sunderland have a zero-tolerance policy towards racism and confirmed their intention to co-operate fully with police in their investigation.
The club said Jones had been banned from the stadium "until the result of the investigation is known".
West Brom manager Steve Clarke has condemned the incident, which comes a month after another supporter was banned from Stamford Bridge for appearing to make a similar gesture.
"There should be no place in the game, or in any walk of life, for some of the things that have transpired within stadiums over the weekend," Clarke said.
"The authorities are now looking into the incident at Sunderland and Romelu has our full support."
When asked to comment after his side's defeat to Swansea on Wednesday, Lukaku said: "I'm sorry, I don't want to talk about it."