I am going to say no to the OP. I mean, we Fiesta'ed Tennessee's faces off without mercy back in the late '90's. That is a historic program full of winning tradition. Overcoming Tennessee and their amazing history of just winning the biggest games is by far our biggest out of conf victory. Second would have to be almost beating Auburn at Auburn in the Prince days.
No matter what happens w mich, the above remains above all else.