Chelsea captain Cesar Azpilicueta has confirmed that teammate Antonio Rudiger approached him after allegedly hearing Tottenham Hotspur fans racially abuse him on Sunday.
The German defender was seen to indicate that some of the fans had been making monkey noises at him - a claim that the Spaniard conveyed to referee Anthony Taylor in line with Premier League regulations.
After Taylor discussed the issue with his fourth official and the two respective managers, the official PA system at the ground issued three separate warnings about racist conduct.
Speaking on Sky Sports News after Chelsea's 2-0 win, Azpilicueta said: "Toni came straight up to me and told me that he was hearing some racist songs about him.
"I reported to the ref immediately and then I left it to the ref to do his job.
"We are very concerned and aware of this behaviour and together we need to stop it."
Tottenham have subsequently announced that they are undertaking a full and thorough investigation into the incident.