The striker admits his four-goal haul is yet to sink in and has warned BVB to finish off the job in the second leg this week
The Poland striker produced an outstanding display as BVB ran out convincing winners in the first-leg of their Champions League semi-final, but Lewandowski has warned the tie is not over yet, as he bids to finish off los Blancos on Tuesday.
"If we don't play as well as we did in the second half, it will be difficult," the 24-year-old told polishfootballonline.com.
"Real Madrid is a fantastic club and will definitely push us to play defensively. We have to look to score in Spain - that will make our job much easier.
"We have to play just as well in the return leg to show that this wasn't an accident.
Lewandowski then recalled a comment made by Pepe during the first leg and looked back on each of his four goals from the finest night of his career to date.
"During one of the last corner kicks, Pepe came up to me and said 'You've scored four goals already, don't you think that's enough?'" he recalled.
"Each goal was different. The first one was from a great pass from Mario Gotze where I got away from Pepe and got my foot to the ball.
"For the second goal, I knew I wasn't offside so I quickly put the ball in at the near post. The third goal was automatic for me. I stopped Mats Hummels' shot, turned and coolly slotted into the top corner. In this situation, the first touch was the most important factor. The fourth was a penalty - nothing to comment on that."
"I am very proud but I think it will completely sink in after the season is over. We have made a huge step to make it to the final, but we are not there yet. I am very happy that we defeated Real Madrid in great style - especially in the second half where they had no chance against us. We played perfectly."