Luis Enrique blamed Paris Saint-Germain's 2-1 home defeat to Atletico Madrid on bad luck, admitting their hopes of Champions League qualification were in danger.
PSG applied their usual possession pattern but were again pretty much toothless in attack, owing Warren Zaire Emery's opener to a defensive blunder.
Nahuel Molina equalised quickly and Atletico's resilience paid off three minutes into injury time thanks to second-half substitute Angel Correa's goal at the end of a counter-attack - a scenario that Luis Enrique labelled a 'bad joke'.
PSG had a handful of clear chances through Achraf Hakimi, Bradley Barcola and Ousmane Dembele but, with no out-and-out striker, were unable to convert.
"There are no words. I think that in our three home games, we were highly superior to our opponents but we did not have any luck," Luis Enrique said.
"As long as there are matches, we will fight," he added, with PSG next set to travel to Bayern Munich on November 26.
PSG are 25th in the 36-team league, just in the elimination zone, midway through the group phase.
They have lost five of their last eight games in the Champions League (W2 D1), as many as in their previous 19 games in the competition, while this is the first time they have failed to win successive home group games in the competition (D1 L1).
On Wednesday, they had 22 attempts on goal to Atletico's four, as they accumulated 2.12 expected goals, with their opponents showing their clinical edge after creating just 0.67.
"I've been in the game for over 30 years and I can't explain it. It's just bad luck. We were infinitely superior to our opponents," Luis Enrique added.
"We would have deserved to win our three home games. Comfortably."
Asked if PSG's chances to go through the league phase were in danger, he said: "Undoubtedly.
"We created 50 chances in three games and we failed to convert so many of them... we need 20 clear chances to score and our opponents sneeze and they score... it sounds like a bad joke.
"Creating chances is the team's responsibility and I'm responsible for the team, so I'm responsible for the results. If I fail, I will fail with my ideas. We're on the right path."