Athletic Bilbao's Nico Williams scored in the 3-1 La Liga defeat at Atletico Madrid after accusing a section of home fans of racially abusing him.
The Spain winger asked referee Juan Martinez to stop the match midway through the first half at Estadio Civitas Metropolitano.
The game was paused to announce to the crowd, and Atletico players Antoine Griezmann and Jose Maria Gimenez appeared to urge their fans to stop chanting before play resumed.
"I have gone to take a corner and I have heard monkey sounds," 21-year-old Williams told DAZN.
"There are stupid people everywhere, but nothing happens. We have to keep working.
"I hope this changes little by little because, in the end, we are fighting internally and externally against this."
Williams was booed by some fans throughout, which intensified when the match was stopped and after he equalised just before half-time.
Talking about his goal celebration, he said: "It comes with a bit of anger.
"It is not normal that they still insult you because of your skin tone."
Williams' brother and team-mate Inaki Williams said: "The jeers should be directed at the people who said the insults and not at the victim."
Writing on social media, Atletico said the club were "against any act of racism or hatred".
A La Liga statement read: "There's no place for racist or hateful behaviour in sport.
"La Liga vehemently condemns any racist acts and will continue working to eradicate this inexcusable behaviour from our sport."
Williams cancelled out Rodrigo de Paul's opener, but Angel Correa's effort early in the second half and an own goal from Athletic goalkeeper Unai Simon earned Atletico victory.
They are six points clear of fifth-placed Athletic with five games remaining this season, leaving them well-positioned to secure Champions League football next season.
Last month Real Madrid filed a complaint with the Spanish legal authorities after a video on social media appeared to show Atletico fans chanting a racist slur about Brazilian forward Vinicius Jr.
