"Of course, it was important to win away against a very good side," Sahin told reporters. "To get the three points is massive.
"For us it was important to stay good defensively and be patient. We knew we would get chances and the chances we got we had to score. We knew that and we did that.
"Lewandowski worked [so hard]. It was great for him to score here and I was happy for him."
Dortmund travel to Schalke 04 in the Bundesliga on Saturday.