Manchester United slumped to a 2-1 defeat to City on Sunday at Old Trafford, but responded tonight with a 1-0 win over Bournemouth tonight.
The Red Devils were far from their best as they earned a scrappy three points against Eddie Howe’s men.
Romelu Lukaku’s header, his 14th goal of the season in all competitions, was enough to separate the two sides.
But when pressed over whether United suffered from a hangover in their defeat to City, Mourinho was unequivocal.
“Fatigue, yes, but hangover – no,” Mourinho said.
“The game was a big one, and a defeat does not help in your recovery – victories help, defeats don’t.
“They were difficult opponents and difficult conditions.
“If we had scored the second it would have been a calm night for us.”
Elsewhere, City kept up their relentless start to the season with a 4-0 win away to Swansea.
United travel to face West Brom next on Sunday (2.15pm).
They remain 11 points behind Manchester City in the table.