The Portuguese tactician slammed the first 45 minutes in his post-match press conference but explained that it changed in the second half.
United went in at the break 1-0 up following a deflected Zlatan Ibrahimovic free-kick but Mourinho criticised the teams lack of intensity.
The United boss also cited reasons such as lack of concentration, slow build up play and no movement in attack as to why he was unhappy.
“I think we were quite lucky to be winning at half-time,” he explained.
Zlatan’s easiest hat-trick
The Swedish star scored one of the easiest hat-tricks he is ever likely to score against Saint-Etienne.
The forward scored a deflected free-kick in the first half before tapping in from two yards to make it two.
Zlatan then made it three from the penalty spot late in the game to seal the matchday ball.
No doubt about it, the star striker will not care how he got the three goals, just that he got all three.