West Ham United boss David Moyes saw Grady Diangana sold to West Brom against his will.
The Sun says the Hammers boss wanted to keep the highly rated academy graduate but owners David Sullivan and David Gold went ahead and agreed an £18million deal with West Brom.
The transfer - which Moyes accepts was done with "aim of strengthening the squad in different areas" - has sparked all-out civil war at the club, with captain Mark Noble and other senior stars voicing their anger on social media.
More than 70,000 West Ham fans have taken to Twitter and agreed with them.
The Hammers suffered an embarrassing 5-3 defeat at home to Championship outfit Bournemouth on Saturday.