I can't decide between 4-5-1 V or 4-2-2-2, both maybe a solution, since he has only got 3 defenders and obviously he looks like he plays attacking football, Your orders are most likely, defending, down both flanks, hard tackling, long balls with counter-attack, tactics top quality teams aren't going to like playing against.

4-5-1 V
---------ST--------
AML------------AMR
-----MC----MC-----
--------DMC--------
DL--DC------DC--DR
---------GK---------

4-2-2-2

-----ST-----ST------
AML-------------AMR
-----MC-----MC------
----------------------
DL--DC------DC---DR
---------GK----------

I think being at home for the first leg since your the underdog, you will get some possession bonus for home support and if your opponent doesn't watch you will get +13%, perhaps 4-2-2-2 would be better choice for the home leg and the 4-5-1 V for the away leg.

If you decide to go ahead with my advice or not, good luck with the cup games anyways.