Chelsea coach Marco Ianni was guilty of celebrating right in front of Mourinho in the United technical area after Ross Barkley scored the Blues’ equaliser in the 96th minute.
Mourinho attempted to confront him and follow him down the tunnel before stewards and staff members intervened to calm down the situation.
Sarri attempts to talk to Mourinho as tensions boil over at Stamford Bridge Sarri confirmed he would take ‘very hard’ action against his staff member and accepts Chelsea were on the wrong side of the situation.
Speaking to Sky Sports after the match, he said: ‘Sincerely I have not seen (what happened) but then I have spoken to Jose (Mourinho) and then, of course, I spoke to the member of my staff.
‘I think we were on the wrong side. I have dealt with this immediately.’ The Italian, however, refused to clarify exactly what sanction he would impose on Ianni or any other staff members involved, insisting he has to deal with the fallout privately to protect his credibility among his staff.
‘I think this is private. I spoke to the member of my staff and I have to be very hard.
Then I cannot come in here and tell everything otherwise I am not credible with my staff. ‘I am not happy as I said before. After I spoke with Jose I understood we were on the wrong side of the situation.’