Here's my prediction for semifinal
With your prediction, the final match will be between two Italy teams: Juventus vs Roma. It looks interesting for Serie A but not for fans as if they meet each other in a final match, that match would be boring. The last time two Italy clubs meet each other in a final match in Europe is Champions League final between AC Milan and Juventus. That is a boring match which was decide by penalty shoot-out.
Sevilla vs juventus
I can't even deny that sevilla was able performing so well against MU by giving so many pressures during the match. In another case, i can't also deny the fact that if meguire, malacia and de gea has been contributing 4 goals to the sevilla. Those guys were helping sevilla to be qualified for semifinal.
As long as juventus will not make same mistake like MU and i think that juventus will able to win against sevilla easily. The main points are if juventus must not make blunders when it will be facing sevilla.
With what Sevilla shown in a second leg to beat Manchester United, we can not under estimate them. However, I believe Juventus defenders won't make mistakes like United players did from De Gea to Maguire.
Juventus can be considered stronger than Sevilla as they have better standing and form in Serie A. However, in semi final, knock-out format, Sevilla are not too weaker than Juventus.
Leverkusen vs roma
The battle between two coaches that have ever become teacher and student in real madrid. I may still prefer to take roma rather than leverkusen. Mou is having various tactis. The tactic that will be used by leverkusne was always related with tiki taka. As long as mou will use the right strategy and it will not work against as roma. As roma has a magnificent coach combined with skillful players. It may make leverkusen will be so hard to beat as roma.
Leverkusen are like Sevilla. They both got troubles in their national leagues but recently have good improvements. Leverkusen even did it better than Sevilla and they are actually a strong opponent for AS Roma. I still believe that Mourinho will help Roma better than Xabi Alonso can do for Leverkusen. Mourinho have had more than 150 matches in European cups and he is very experienced there. It is what we won't see in a young coach like Xabi Alonso.