Ok that will be ok, if you have a AMC then play him in behind aswell!, if you want to be cautious just start with the two STs then at half time bring on the AMC for some extra fire power if your struggling, I like to have a DMC playing in the center as I only play 3 at the back but I always take him off around HT -60min mark to put on a 3rd ST, as I said before the key to this is the open space he has left in the wide areas of midfield!, flank players is most definatly deeded here.