Last time I bought a roast that size,I left it in the fridge for 5
days.When I pulled it out to cook it,it stunk.Threw it away. Depending
on how you cook it,you may want to start with it frozen anyway.if you
do them in a crock pot,you'll never know the difference. I like to do
mine in my dutch oven,frozen,for about 40-50 minutes,with broth and
veggies,or broth and sauer kraut.[Leaves the inside a bit rare-poormans
prime rib!!]