The Italian soccer federation launched an investigation on Wednesday after AC Milan midfielder Kevin Constant walked off the field following racist abuse during a friendly match.

The incident took place Tuesday during a 2-1 friendly loss to home side Sassuolo in the Trofeo TIM tournament, which also involved Serie A champion Juventus.

Constant, who is black, walked off the field after kicking the ball into the stands in the 34th minute, emulating the actions of Kevin-Prince Boateng last season. The referee allowed a substitute to come on and also ordered an announcement warning that the game would be suspended if further incidents occurred.

Following racist abuse during a friendly in January against Pro Patria, Boateng also kicked the ball at a section of the crowd before walking off the field with the rest of the Milan team.

Milan has not commented on the incident but shortly afterward Constant tweeted a mock-up movie poster of teammates Boateng, Mario Balotelli and M'Baye Niang and the title ''Stop Racism.''

Sassuolo is about to start its first ever season in Serie A after winning the second division last season.