Mauricio Pochettino says he has had trouble sleeping since Paris Saint-Germain's elimination from the Champions League at the hands of Real Madrid.
The French giants had a one-goal advantage from the first leg and took the lead in the second leg on Wednesday.
But Pochettino's team ended up conceding three times in the second half of the clash in Madrid, with Karim Benzema's hat-trick sending the Spanish side into the quarter-finals.
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What has been said?
The defeat came as a major blow for Pochettino, who admits he is still outraged by the way his team surrendered control of the tie.
"We are disappointed and so are the players and the whole club," he told reporters.
"We took a big blow and the last few days have been difficult. There was not much rest and we don't have much energy.
"We know that we have the responsibility to win the game on Sunday. And in relation to the reception of the fans, it will look like what the fans have decided to do and we understand their disappointment."
Asked how he feels personally, Pochettino said: "Hurt. Very upset. If we analyse the two games, here in Paris the whole game and the first 60 minutes in Madrid, the team was superior.
"The way we lost pisses me off, sorry for the word. I have rage, I feel a certain malaise, it's difficult to sleep at night, but we must assume our responsibilities, to continue, to think about the Ligue 1 title.
"Personally, mentally I am in the middle of the recovery process. This does not mean that I am not strong, I feel ready to fight and take up this challenge."
What next for PSG?
The Paris club have suffered two defeats in a row, having gone down 1-0 to Nice in Ligue 1 before taking on Madrid.
They are still 13 points clear at the top of the French top flight, however.
Pochettino's team are in action again on Sunday when they face Bordeaux, which will be followed by a trip to Monaco next week.