Sussex Police has appealed for information after a man was heard shouting racial abuse at Tuesday’s match between Crawley Town Football Club and Port Vale.
Officers say they have a suspect but are appealing for witnesses to gather more information.
Football liaison officer Sergeant Darren Taylor said: “We have launched an investigation into reports from a number of Crawley Town fans who were upset at racial abuse aimed at a Port Vale player during the match on Tuesday evening (October 22).
“The man was sitting amongst home fans in the West Stand at the Broadfield Stadium and is reported to have been shouting out comments of a racial nature throughout the match. This is fairly unusual nowadays but still clearly unacceptable.
“Fans were obviously very upset and we are working closely with the club who are being very supportive. They obviously want to stamp out this sort of behaviour straight away.
“A number of witnesses have already come forward and we do have a suspect, but we would like to hear from anyone else with information to call us on 101.”