Zinedine Zidane felt Real Madrid did not deserve to lose against Espanyol, despite admitting they were poor in the second half at the RCDE Stadium.
The champions saw their five-game winning run in all competitions emphatically ended when Gerard Moreno slammed home a dramatic late winner for lowly Espanyol.
The 1-0 defeat will lead to questions over Zidane's decision to rest Cristiano Ronaldo, while Karim Benzema started the midweek fixture on the bench.
Benzema did come on as Madrid pushed for a late winner, only to be caught on the counter when Sergio Garcia's cross allowed Moreno to score in the third minute of added time.
"We have missed a bit of everything. We started well and had chances to score, but the second half was worse," Zidane said.
"Espanyol had few opportunities. It is a defeat that hurts and a bad result - I'm sorry for the players.
"Sometimes you do not understand football. We had a few moments in the second half, but you have to accept the difficult times.
"When time is nearly up and it's 0-0, things can happen. We always look for victory and today we did not achieve it.
"They also scored a goal in the last minute, but we should not think twice about that. We did not deserve victory, or defeat. "
Zidane - who withdrew Gareth Bale with nine minutes remaining when the game was still scoreless - could see his side slip down to fourth in the table, if nearest rivals Valencia win away at Athletic Bilbao on Wednesday.
They will look to get back to winning ways when they host Getafe this weekend, followed by a huge Champions League clash with Paris Saint-Germain in the French capital next Tuesday.
3 - Espanyol are unbeaten in their three La Liga home games against Barcelona, Real Madrid and Atletico in the same season for the first time since 1997/98. Battling. pic.twitter.com/EQDZC2vX3m-- OptaJose (@OptaJose) February 27, 2018