I am playing against this formation for the second time. The 1st time I barely won using a classic 4-4-2...and I'll be out of the cup if I lose this time. Isn't it illegal?? How can a play him???

This is the formation he is playing:

--------GK---------
-DR--DC---DC--DL-
--------DMC-------
--------MC--------
--------AMC-------
--ST---ST---ST----

Thank you for your time and help.