A bit late now, but one of the tricks chefs use with tougher cuts of meat is to coat them in oil and leave them covered in the fridge for a couple of days.
Take it out of the fridge and let it come to room temp before you cook it. Make sure you rest it for a few minutes before you eat it after cooking. I usually put mine on a rack and cover it in foil. It's worth the wait. Have a lovely meal.