It is not sure that AS Roma can defeat AC Milan. Many people assume AC Milan is still better than AS Roma. I can understand that people favor AC Milan because AC Milan has a better experience and history in international matches. If we learn the current performance of these teams, I think both AC Milan and AS Roma has almost the same chance. But AS Roma seems to have more injured players.
Sanches, Dybala and Smalling will back on early April, so they only have 3 injured players during the match if there's no more new injured player. Milan was strong during 90's, now they're like a mediocre team. Since Roma is more stable even though they're made nothing in Serie A, but Roma is better than Milan. The first leg will held on San Siro, if the match ends in draw or Roma's win, I believe Roma will definitely qualify to the round.