Paul Pogba's injury threw Manchester United because it forced them to start an unfit Marouane Fellaini in Sunday's 3-1 derby defeat to Manchester City, according to Jose Mourinho.
Reports on Friday claimed Pogba was a doubt after missing training and such speculation proved to be accurate, with the France international missing the game at the Etihad Stadium.
Without Pogba United struggled in midfield, with the trio of Ander Herrera, Nemanja Matic and Fellaini offering little expertise in possession.
And while Mourinho rued Pogba's absence, he actually placed more importance on how the injury forced Fellaini to play a full 90 minutes earlier than he should have.