United suffered a shock 2-1 defeat at Old Trafford at the hands of LaLiga side Sevilla, who they played out to a 0-0 draw in the first-leg last month.
And after the lacklustre display at the Theatre of Dreams, the former Real Madrid coach took responsibility for their failure to advance to the quarter-final stage of Europe's elite club competition.
"When a team win, everyone wins, but when a team loses, the coach loses," he said after the game, as quoted by Marca. "It's the same everywhere, in England, in Spain and in China. I have lost and clearly, I have made mistakes."
However, the Portuguese tactician played down the notion that the defeat marks a crisis for the three-time European champions.
"I sat in this chair twice in the Champions League after knocking out Manchester United [in the last 16] at home, at Old Trafford," he said, according to BBC Football.
"In this chair with Porto (in 2004) and Real Madrid (in 2013), they are out both times. It is not something new for the club."