Professional Footballers' Association chief executive Gordon Taylor has criticised Sunderland manager Paolo Di Canio for taking discipline out against a number of his players.
The former Swindon Town boss has publicly hit out against a number of "arrogant" players, as well as issued fines of two weeks' wages for those who were deemed guilty of unprofessional behaviour.
Reports have emerged claiming that a handful of players, one thought to be defender Phil Bardsley, have complained to the PFA over Di Canio's recent discipline.
"He cannot be a law unto himself," Taylor told The Mirror. "We're aware of player unrest at some comments made publicly, and other situations. A number of players are involved.
"We're aware of Paolo Di Canio's comments. It's something we had to deal with at Swindon as well. Our rules for discipline are agreed with the Premier League and Football Association."
Di Canio replaced Martin O'Neill at the Stadium of Light and managed to save the North East side from relegation to the Championship.