Zinedine Zidane admitted Real Madrid may have paid the price for their Clasico exertions in Wednesday's Champions League defeat to Wolfsburg.
Madrid suffered a surprise 2-0 loss in Germany just four days after claiming a hard-fought 2-1 win at Barcelona in La Liga.
And head coach Zidane feels that victory at Camp Nou could have had a negative impact on their display at the Volkswagen Arena, although he remains hopeful of a comeback in the second leg of their quarter-final tie next week.
"Perhaps physically, yes," Zidane told a news conference when asked if Madrid had struggled to play at their best after the Clasico.
"We didn't start with the right amount of intensity for a Champions League game. They did. In football you make errors and we didn't start with intensity.
"What we have done recently has been positive and I'm not going to go crazy.
"Being Real Madrid we are capable of great things."