Jose Mourinho claims he was stung into action by Manchester United's 4-0 humbling by Chelsea at the weekend.
United bounced back from that heavy loss by edging a tight derby against Manchester City to claim a place in the EFL Cup quarter-finals.
Manager Mourinho felt it was time to show his fighting qualities and thanked fans and players for helping deliver an important result.
The Portuguese told MUTV: "The only thing I can say is I couldn't be prouder than I am to be Man Utd manager. As I wrote in my notes, the only way I know is to fight, to work and fight. The players did that for the fans, and the fans did that for the players too, because they also played this game.
"This is not the Champions League final, it is just the League Cup last 16, but it is against City and it is after a big defeat, so it was very important for us."
Juan Mata scored the only goal of the game after 54 minutes as United enjoyed a brief spell of dominance that also saw Paul Pogba have a shot touched onto the post by Willy Caballero.
Mourinho, who did not hold a formal press conference, added on Sky Sports: "I'm happy the players did everything and they deserved to win. In the last week everything went against us but we are professionals.
"The fans felt deeply such a negative result and today was a good chance to clean that feeling because it's a derby and knock-out, and to win against Man City gives everyone a better feeling. I'm especially happy for the players and fans."
The result was another one of disappointment for City, who after opening the season with 10 successive victories have now failed to win in six.
That equals the longest winless run of manager Pep Guardiola's career, but the Catalan is convinced his side will soon come good again.
Guardiola, who made nine changes for the game, said: "Sometimes it happens in __football the manager doesn't win. Sometimes you win, sometimes not.
"It is the first time, okay, but hopefully it does not happen again in my career. We have had these six times but we are going to change it as soon as possible."
City failed to register a shot on target during the 90 minutes.
But Guardiola said: "Congratulations to United, they made a good performance. We had no normal chances. We had chances on the counter-attack but with no last pass.
"But we controlled their long balls with their tall guys and I am happy for the performance of the players who don't normally play. So, no regrets. We will improve."
City captain Vincent Kompany, who is easing himself back into action after a groin injury, was substituted at half-time. Guardiola confirmed this was merely avoiding taking a risk.
He said: "He told us he is tired and was not ready to play the second half. That is why we made the substitution.
"He felt not good but the important thing is he is not injured. That is a good step."
Mourinho had earlier apologised to the supporters in his programme notes for their 4-0 defeat to Chelsea.
The former Chelsea manager endured a nightmare return to Stamford Bridge as United were brushed aside 4-0.
It was United's heaviest away league defeat since 1999 and was also Mourinho's biggest loss as a Premier League manager.
He wrote: "As the leader of this squad I want to start by saying sorry to all the Manchester United fans around the world. Sunday's 4-0 defeat at Chelsea was not a United result; it was a result that has made us all extremely sorry for all our supporters and we apologise for it.
"Once again at Stamford Bridge our fans were sensational. I cannot think of another set of supporters who would be singing for 90 minutes like that when their team was losing. They were a credit to the club and I feel so sorry for them that the result could not match their performance.
"Even in the best periods of the club's history there have been heavy defeats - I have beaten United 3-0 as a manager and 3-1 twice - but we all know that we cannot accept result like the one we had on Sunday. There is only one way I know to react to this kind of result and that is with hard work.
"Tonight we play against another top team as we welcome Manchester City to Old Trafford. I can say for sure that they are also unhappy with their current situation, having suffered their own 4-0 defeat in Barcelona a week ago and coming into tonight's game without a win in five games, but that does not change the fact that they are a very good team with a very good manager and very good, experienced players.
"We have our problems and the biggest one of all is that Eric Bailly suffered an injury at Chelsea which will force him to miss many matches. Eric has started his first season at United very well indeed and it is a real shame for him and for us that he will now be on the sidelines. The same applies to Phil Jones, who is in the same situation.
"But while it is sad news for Eric, we have a big match tonight which has to demand our full focus. Cup matches are great, they always guarantee a super atmosphere and I know that will especially be the case against our city rivals tonight.
"I will be there with you all on the touchline and together we will all support and push our players to give the 101 per cent effort required in this kind of match."