Porto's Mali international striker Moussa Marega walked off the pitch in disgust after being subjected to a torrent of monkey chants in a stormy Portuguese league game at Vitoria Guimaeres on Sunday.
The 28-year-old had scored a 60th-minute winner for Porto against his former club which sparked the home fans to aim even more vitriol at the France-born player which had started as early as the pre-match warm-up.
In the 71st minute, Marega signalled to the bench that he was walking off in protest even though teammates, Porto coach Sergio Conceicao and Vitoria players tried to get him to stay on the pitch.
As he walked off, an angry and upset Marega gave a thumbs-down signal with both gloved hands to the home fans.
He had already been given a yellow card for his goal celebration.
Marega played for Vitoria Guimaeres from 2016-2017 on loan from Porto, scoring 13 goals in 25 games.
Marega later wrote on Instagram after the game, which Porto won 2-1, that his tormentors were "idiots who come to the stadium just to make racist chants."
"And I also thank the referees for not protecting me and for giving me a yellow card because I am defending my skin colour.
"I hope I will never see you again on a football field. You are a disgrace."
Conceicao blasted the home fans before posting a photo of his player on social media with the message: "We are all Moussa." "We are completely indignant at what happened," he added.
"We know the passion that exists at Vitoria and I think that most fans do not recognise themselves in the attitude of other people who insulted Moussa.
"We are a family, regardless of nationality, skin or hair colour. We are all human, we deserve respect. What has happened here is lamentable."
Vitoria Guimaraes or the Portuguese football federation were yet to comment on the incident.
Sporting Lisbon, one of Porto's bitterest rivals, issued a statement supporting Marega and "repudiating any act of racism or social prejudice".