Perotti (penalty) and Edin Dzeko struck the goals for the Giallorosso as they reached the round of 32.
“I had said these are strange games where anything can happen. We did not play well, but we got through and must now look forward to the next round," Perotti told Sky Sport Italia.
“I think we didn't have the right attitude, as we were distracted and perhaps thought it'd be easy. Wolfsberg were already eliminated, but they fought hard, pressed us constantly and we need to improve in many areas if we want to go far.
“When we saw that we were struggling, we gave 100 per cent and perhaps it was a bit late by that point. I have no doubts over my teammates and what we intend to do, but I do feel we had the wrong attitude at times."