Real Madrid Castilla midfielder Cristian Cedres was reportedly targeted by supporters as they attacked his car while he was leaving training.
The 19-year-old, who is yet to progress into the first team, took to social media to urge the fans to be "united" after a group kicked his vehicle while he was driving out of the facility.
Cedres tweeted: "It is not normal to leave training and receive insults and blows to your car. Now is when all of Real Madrid must be united. Hala Madrid."
According to Mundo Deportivo, fans, who are angry following Madrid's 4-0 defeat to Barcelona at the Bernabeu on Saturday, targeted the vehicle as they believed that he was one of the first team players.
Last night, club president Florentino Perez gave his "support and confidence" to manager Rafael Benitez following the weekend's result.