Barcelona midfielder Frenkie de Jong was targeted with verbal abuse as he drove to work on Wednesday.
As the 25-year-old approached Barcelona's training center, a man outside was filmed screaming: "Lower your salary, b****!"
The ugly scene came amid what is turning into a high-profile standoff between the club and De Jong regarding his contract.
De Jong is under contract at the Camp Nou until June 2026, having signed a lucrative extension in October 2020.
According to The Athletic, a condition of that deal, which was signed during the COVID pandemic, was that De Jong's salary would be temporarily reduced during the 2020/21 and 2021/22 seasons.
The total amount of deferred payments is said to add up to €18 million, which was supposed to be paid to De Jong over the course of the final four years of his contract, starting this summer.
But Barca no longer intend to pay De Jong this amount.
De Jong's new contract was signed shortly before former club president Josep Bartomeu and the entire former board of directors resigned.
Leading figures at the club are now suggesting that Bartomeu signed De Jong's contract extension illegally and that it should be annulled, thus reinstating his previous deal, which was signed in January 2019, includes a lower salary and would be due to expire in June 2024.
As well as trying to avoid paying De Jong the full amount of his controversial contract, Barca are said to be keen to sell him to boost the club's precarious financial position.
Manchester United had an offer worth £72m for De Jong accepted earlier this summer, according to Sky Sports, but the player snubbed the move.
De Jong's reluctance to join United was in part due to him wanting to play Champions League soccer - something not currently on offer at Old Trafford.
But, as reported by Sky, Chelsea - who have qualified for this season's Champions League group stage - are now ready to match United's offer of £72m.