"De Jong should consider legal action v Barcelona and all players should be behind him!" Man United legend and former Valencia head coach Gary Neville tweeted.
"A club spending fortunes on new players whilst not paying the ones they have under contract their full money is immoral and a breach.
"FIFPRO should be all over bullying like this and stop it."
It's been heavily reported that Barcelona are trying to offload Frenkie de Jong and demand he takes a pay cut to stay with the team.
The midfielder already earns less than what his contract stipulates though. He received just €3m in the 2020/21 season and then €6m in the 2021/22 season in order to help Barca survive the pandemic.
Under his current deal, he is due to earn €18m next season for the next three years, before a €19m pay-off for the 2025/26 campaign.
