Exeter City have launched an investigation after a Northampton player complained of an alleged racist comment during Tuesday night's Papa John's Trophy game St James Park.
A Northampton player spoke to the match referee Carl Brook to voice his concern about something that was said from a spectator in the crowd.
Exeter told Sky Sports News on Wednesday morning that a full investigation has been launched and police are also investigating. The club say the process of looking through CCTV footage is underway.
Northampton, in a statement on Wednesday, said: "Northampton Town Football Club are aware of an alleged discriminatory comment made by a supporter towards one of our players at Tuesday's Papa John's Trophy tie with Exeter City.
"This was reported by our player to the match referee in the correct way so the matter can be investigated and we will continue to support that process with both the authorities and Exeter City Football Club.
"The player concerned has the club's complete support in this matter."
Northampton - in a repeat of last season's League Two play-off final - won the tie 2-1 thanks to Benny Ashley-Seal's strike eight minutes from time to knock Exeter out of the competition.
The allegations overshadowed the return of supporters to St James Park for the first time in 280 days, with 714 fans in attendance for the game.
Kick It Out: Players right to walk off in PSG-Basaksehir game
Kick It Out chair Sanjay Bhandari says he is "deeply disturbed" by the allegations that a match official used racist language in Tuesday's Champions League match between Paris Saint-Germain and Istanbul Basaksehir.
Romanian fourth official Sebastian Coltescu is alleged to have used a racist term when identifying Basaksehir's assistant coach, Pierre Webo, during an incident in the 14th minute of the match.
Webo was shown a red card during the exchange on the touchline and the match was later suspended when Basaksehir and Paris Saint-Germain players walked off the pitch, with the game rescheduled for Wednesday with a new team of match officials.
Bhandari believes the players were right to walk off in protest. When asked for his reaction to the events in Paris, he told Sky Sports News: "I'm really saddened to see that and deeply disturbed that it's come from a match official."
Millwall vs QPR: Fans applaud as visiting players take a knee
Millwall fans applauded as their players remained standing and QPR players took a knee ahead of their Championship fixture at The Den on Tuesday night.
In contrast to Saturday's game against Derby, there were no boos heard as QPR players and match officials took a knee. Millwall's Mahlon Romeo raised his fist but no players from the home side opted to take a knee.
Both sets of players also linked arms and held aloft a banner which said 'Inequality' with the 'In' crossed out, as a show of solidarity against racism and other social injustices.
Millwall also wore Kick It Out's logo on their matchday shirts in place of one of their main sponsors, Huski Chocolate.