Chelsea have lodged a complaint with UEFA over alleged racial abuse aimed at Callum Hudson-Odoi during the Europa League game at Dynamo Kiev last week.
The 18-year-old winger was allegedly on the receiving end of monkey chants from the crowd shortly before the final whistle of Chelsea's 5-0 last 16, second leg victory.
The incident took place at the end Chelsea were attacking in the second half and the teenager instantly brought it to the attention of team-mate Cesar Azpilicueta, reports the London Evening Standard.
The Chelsea captain told referee Tobias Stieler when the game concluded and pointed to the section of the ground where the noise allegedly came from.
Hudson-Odoi brought it to the club's attention afterwards and chairman Bruce Buck and club secretary David Barnard reported the matter to the Uefa match delegate.
In a statement, a Chelsea spokesman said: “We can confirm a report of racist abuse directed at one of our players in the final minutes of the match in Kiev from a small section of home supporters. We wholeheartedly condemn such abhorrent behaviour.
“We expect Uefa to conduct a fulsome investigation and we will provide full cooperation."