I've got a unit of kataphraktoi facing another unit of kataphraktoi. Both are valour six, command seven, and full.

How can I win this battle on Expert? If I lose, my campaign is screwed. I play where I don't go back a save if I lose a battle, and if I lose this one, my Turkish Empire will be reamed by the might of a massive Byzantine army (over seven full stacks). If I win, I just might pull through and defend my territory with only minimal losses. Please help me!