Before the match, Mourinho exchanged words with the Manchester United coach as Paul Pogba appeared confused over tactical instructions.
Cerra's role is to provide video analysis of opposition sides, but the Ukranian opposition changed their team before the game, meaning Pogba was unsure over instructions.
'It was set pieces, organisation, they changed their team before the game," the Man Utd manager said.
'Paul was a bit confused with the changes and obviously I want my assistants to take care of all the details".