If he keep changing his formation then let him to use counter for your best formation and you take action from that point. I mean set your best player on top 11 then fight
anyway, for 4-2-3-1 I use 4-1-4-1 or 4-4-2 and for 4-3-2-1 I use butterfly.
if you have good position for 4-1-4-1 or 3n-3w-3n-1 then let him counter you but I don't think he going to counter you cuz he need to defend his 5:2 win, its mean you need 3-0 win, good luck.