Actually, Mourinho is the main reason many people think Roma is going to win this game otherwise Roma is not a strong team in a good situation to beat Leverkusen especially when we consider the recent performance of Leverkusen and how they won Bayern Munich this season, that's why we can even expect to see them winning the game against Roma easily.
I mean he does have a great amount of talent when it comes to these type of games and that is why we are going to end up seeing them win. He has been a great tournament coach ever since he started coaching, that's his thing. Sure he is good when it comes to league, there is no doubt about that because he is overall a good manager to begin with, but his league record in the past is not as good as his tournament records, there are seasons where he won UCL and lost the league title.
This is why many people think that there is a chance he could end up getting a win here, and I bet that he is not going to be that troubled when it comes to this game as well. He will figure out a way to get the win, whatever he has to do, and he will get it done, he will give his players the advantage they need, the leverage over the other team.