As with any really good team with a B10 schedule, this is a very tricky question. If you ask me to name all of the teams that I think have an honest, legitimate shot at upsetting us this year, I would say:
Penn State
Minnesota
Iowa
Illinois
Miami
Michigan State
Of these teams, I think the most likely, and the most obvious, is Penn State. Think about it...Glenn Mason has never played the Buckeyes well. He just doesn't scare me. He's got some scary good players, but I just don't see it. Iowa? No way. Iowa is EXACTLY like Penn State when it comes to playing the Bucks. They're almost unbeatable at home, and they can't hardly win in the 'Shoe. Illinois? Nope, they're just not good enough. Even if we play down, and they play way above their potential, we're too much for them. Miami...well, Miami scares me a little. This game is extremely easy to overlook, and to tell the truth, if we didn't play them the first game of the season, they would scare me a lot more. But, while the players may well be looking ahead a little to Texas, Miami is still the very first game of the year, and the boys will be pumped. No way can Miami pull of an upset in those circumstances. Michigan State scares me even more. To be honest, though, I really don't think they have the weapons to beat us. OSU also traditionally plays them well, and that 98 loss is still very vivid the minds of the coaches and players.
Penn State, to me, is the clear choice. Everyone has mentioned the fact that it's a night game, and it's at Happy Valley, and JoePa plays us well, etc., etc. All very valid. All very good reasons why I think they have the best shot. A turnover or two could swing this game, and that scares the piss out of me.