Real Madrid coach Zinedine Zidane admitted he was surprised by his side's slow start as they slumped to a second defeat in four days, 2-1 at home to Celta Vigo in the first leg of their Copa del Rey quarter-final on Wednesday.
Zidane's men hadn't lost in a Spanish record 40 games stretching back to April last year before conceding twice in the final five minutes to lose 2-1 at Sevilla on Sunday.
And Zidane believes the European champions suffered a hangover from that disappointment in a first 45 minutes devoid of goalmouth action at a frigid Santiago Bernabeu with temperatures plummeting below zero degrees
"It was a strange game, especially the start," said Zidane.
"We have to analyse it, something is wrong for sure. We didn't do what we had prepared to do, especially the intensity. The intensity wasn't good at the start of the game."
However, the real damage to the hosts was done in a six-minute spell midway through the second-half as Celta grabbed two vital away goals and their first win at the Bernabeu in a decade.
Iago Aspas's 15th goal of the season put the visitors in front before Marcelo equalised with a sensational volley five minutes later.
However, Celta went immediately back in front when left-back Jonny exploited a huge gap in the centre of the Madrid defence to slot home.
The sides meet again for the second leg on January 25.