Although the Armenian did not score on the night, he played a key role as Dortmund countered at pace on a number of occasions and the win means that qualification is now in the German side's hands.
"I think it was a great performance from Borussia Dortmund," he told UEFA.com. "All my teammates did a great job. We needed to win this game because we lost our last three, so we had to win tonight.
"I would have liked to have scored but I was not able to and there is nothing I can do about it. I have to keep working and not give up. I need to do my best to help the team. It is not important whether I score or not, the most important thing is that the team win.
"We created a lot of chances, even when the score was 2-1 because there were more spaces in the Napoli defence. We were able to counterattack more, which we managed to do and scored the third."
Dortmund and Napoli are both on nine points, behind Arsenal with 12.