Lewandowski scored twice against his former club as Barca won the first-leg of their quarterfinal 4-0 at Montjuic stadium.
The Pole said afterwards: "I'm very happy with my numbers. 99 goals for Barça. In my mind, I always have to help the team as well as score. As a striker, you always have to think about goals, but if we play well as a team, it's easier for me.
"We played as a team, that's the most important thing. Whether Lamine, Raphinha, or I score... we do it for Barça. If we play well together and are in good shape, also off the pitch, this team has a lot of potential. We have four more steps ahead."
However, he doesn't see the tie as a foregone conclusion because "in Dortmund we have to play the same or better. We always have to be prepared.
"This is the Champions League and we always want to be at our best."