The Belgium international knocked a backpass straight to Joselu, who slotted the former Chelsea goalkeeper's stray ball into an empty net.

Casemiro grabbed a late consolation, but there was to be no dramatic finale as Real were left six points behind joint leaders Real Sociedad and rivals Atletico Madrid.

"I have no explanation tonight. It was a mix of good and bad moments," Zidane said.

"Especially at the beginning, when they score a goal at three minutes, we have time to return to the game but things became complicated for us.

"It is difficult because the other day in Milan (in the Champions League) we played a very good game, but also three days later, then we are making a game like this at home.

"What we are going to do is keep working, trying to get all the players back and then change the dynamics. We do not have regularity in our matches and in our results."

Zidane added at a press conference, reported by the Real Madrid website: "After the goal at the end of the first half, we were a little better, but in the second, what we did fell short.

"Now we are going to think about the (Champions League) game (against Shakhtar Donetsk) on Tuesday.

"What I am going to say to the players is going to stay in there (the dressing room).

"I am responsible for all this and I have to find the solution with them, so this is what we are going to try to do.

"Nor should you be thinking about the negative as today's result – we have to see what we did well and go down that path and have more regularity in what we all do on the pitch."

It is hoped Hazard's problem stemmed from just a blow to his leg, rather than anything more severe.

"It is not something muscular, it is what he said," Zidane added.