NFL Fantasy Football Championship Week...starting QB and defense dilemma?

I am entering the championship week in my fantasy football league and would love some help on my starting lineup...It's extremely vital that I play the right QB and defense this week. For my QB, I have to decide between Matt Schaub (playing Miami) or Philip Rivers (playing Tennessee)...Tough right??? As far as defenses go, I have either the Denver Broncos or Minnesota Vikings. Denver plays a tough and explosive Eagle offense while the Vikings, who haven't been playing all that great as of late, get the Bears in Chicago on a Monday Night. Who would you start? Thanks in advance to all those that respond.