Back-to-back defeats threatened to derail Chelsea's season as last weekend's 1-0 win at Crystal Palace dealt a blow to their Premier League title chances, while they slumped to a midweek 3-1 Champions League quarter-final first-leg defeat in Paris.
Mourinho was left fuming after the Blues conceded a late third to PSG and his side responded with a disciplined display against Stoke on Saturday.
Chelsea face an uphill struggle in Tuesday's return leg, but Mourinho believes his men will head into the match on a high after putting their title campaign back on track.
"A third defeat would be very bad for our confidence in relation to Tuesday's match," he said.
"It was important to win, to have again a smile on the players' faces and to get more confidence.
"Now we can approach the match against Paris with a smile. It's what we need for such a difficult match and such an almost impossible job to do.
"I think the best way to try to do it is to have a smile and go at them.
"I want to enjoy that game. I enjoy the difficulty.
"Now we know that we need to win 2-0, 3-1, 4-1, 5-2. We know that we need a crazy result against Paris.
"We must be ready to go without fear, go at them and no problems and see what happens.
"If we have to lose to lose after a magnificent night of football, a magnificent night of emotion, if we have to lose."
The Blues have kept clean sheets in all of their last eight home matches and Mourinho has called for more miserly defending against the French side, who will be without injured striker Zlatan Ibrahimovic.
"If you concede one goal against Paris or a clean sheet, we have a chance," he said.
"If we concede two goals and we have to score five, we can't do the job. It's important to defend well against Paris.
"A clean sheet would be perfect, but even if we concede one goal we will have always a chance to give them a fight."