The centre-back pulled no punches in his analysis of a comprehensive loss in Signal Iduna Park, and stated that Real Madrid would have to attack from the start in the second leg
The Blancos were overwhelmed by a stunning exhibition of finishing by Robert Lewandowski, who netted all of his side's goals as they inflicted a punishing defeat on their rivals. Madrid were given a lifeline by Cristiano Ronaldo's away goal, but will have to turn around a three-goal deficit on home soil if they wish to reach the final.
Speaking after the final whistle, Ramos recognised his team were defeated by a far superior outfit.
"We had no attitude. They were better, that's all. We still got 90 minutes but it's so difficult with a German team," the centre-back confided when questioned by reporters on Wednesday evening.
"People thought we were lucky, but they are a good team. Team spirit and the hard work won today."
Asked whether he thought Madrid's hopes were still alive in the tournament, Sergio gave a tepid response.
"It will be difficult to pass [into the final]. We must try hard from the begining to have options in this competition," he added.
Madrid will host Dortmund in the Santiago Bernabeu on April 30, knowing they must score at least three times to have a chance of reaching the final.