The Everton midfielder received a round of applause from his Everton teammates after issuing an apology for his extraordinary dismissal during Monday's victory at Old Trafford.
The midfielder became the first Premier League player to be dismissed for striking a teammate in nearly two decades when he slapped his defensive colleague during the match. The Toffees' display was heroic as they played with a man down for the majority of the game, including stoppage time, to secure David Moyes' first win at Old Trafford as a away coach in multiple tries.
'My first apology goes to Michael Keane,' he wrote on social media. 'I accept complete responsibility for my actions.'
The Senegalese international did not get an chance to converse with the manager or his teammates at half-time. Afterwards, with the away dressing room buzzing after the 1-0 win, the veteran asked to speak to the whole team and the defender in particular.
The 36-year-old could still be punished by Everton despite the manager's statement that he likes his players competing with each other. The Scot has a standard punishment process for red and yellow cards, including fines, which is likely to be applied in this situation.
The Merseyside club may find themselves without their influential player until the January. The Senegalese international will serve a three-match ban against Newcastle United, Bournemouth and Forest but might be selected for AFCON responsibilities by Senegal before he can return to play against Chelsea on 13 December.
'Passions can sometimes overflow,' he added. 'But nothing justifies such behaviour.'
Meanwhile, Mathijs de Ligt accused United of lacking immediacy in Monday's defeat, which ended their winning streak at multiple matches.
United travel to Selhurst Park for Sunday's lunchtime start. 'Our upcoming match is absolutely crucial,' said De Ligt. 'We have to bounce back from this performance.'