Until the two teams meet, why not root for your team, but be glad for the other team if it is having success? It is a credit to our state for either team to be known on the national scene.
I'm weary of hearing "I'm for (Clemson or Carolina) and for whichever team is playing (the opposite in-state team). I'm weary of hearing "It will be a great weekend if my team wins and the other team loses." I'm weary of hearing fans get very quiet when their own team is having trouble but the other is doing well, then "rubbing it in" when the reverse is true.
There is an unnecessary unkindness in that that is especially uncalled for in Christians. Be for your team. Root as loud as you can. And be against the other team when the two teams meet. But hope that the other team comes into the cross-state meeting with a 11-0 - or thereabouts - record! After all, that makes for a better game anyway.