Sunderland manager Simon Grayson made the under-fire players do a double training session yesterday – including midfielder Darron Gibson.
Irish international Gibson is facing disciplinary proceedings after implying at the weekend that a number of his team-mates did not want to play for the club.
The exchange with fans was filmed, with the midfielder seemingly unaware, and published on social media.
Gibson apologised yesterday morning as the side stepped up their preparations for the Championship season.
Manager Grayson led the side in a double training session following the dire 5-0 defeat to Celtic at the weekend.
He has said that he hopes his side will be a ‘different animal’ when the campaign kicks off at home to Derby County on Friday night, but the Gibson controversy provides another unwelcome distraction at the end of what has been a turbulent summer.
A club statement read: “Darron Gibson has not conducted himself in a manner befitting Sunderland Football Club. As a consequence, we will initiate our internal disciplinary process to deal with the matter.
“Darron has apologised this morning.”
Sunderland’s opponents remain hopeful of making additions to their squad before the televised game.
The Rams are understood to have an interest in Leicester winger Tom Lawrence, who starred while on loan at Ipswich Town last season, as well as Arsenal midfielder Jon Toral.
Manager Gary Rowett said: “I understand at this stage that some people have the opinion that we are not doing anything or we are not trying to do anything or we think we are alright.
“We don’t, we are and we are working incredibly hard.
“Behind the scenes in the past two months we have literally been trying to do deals every single day.
“Of course, they are never easy to do unless you hugely over pay.
“You can get any deal done if you pay stupid money but the reality is we don’t want to do that and I don’t think it is the right thing for this club to be doing that, at this moment.”