The BVB boss believes Tuesday's game will be remembered for years to come - regardless of which team emerges victorious
Die Schwarzgelben ran out 4-1 winners in the first-leg last Wednesday, making them strong favourites at the Santiago Bernabeu, and the BVB boss is expecting a special evening.
"We know what can happen in football, either way, something historic will happen," the 45-year-old told reporters at the pre-match press conference.
"If we go through, it will be historic, if Madrid turn the tie, it will be historic as well.
"My players cannot fail tomorrow, they can only give their best, there's no doubt about this. We have to show that BVB will do everything in their power to reach the final.
"We don't have the feeling of already being in the final. But we have built us a solid foundation, which we didn't expect. We're not in the final yet, but we're fighting for it."
Madrid and Dortmund kick off at 20.45CET on Tuesday, April 30 at the Santiago Bernabeu.