What a difference a week makes.

Seven days ago, Michigan fans didn't even know who was going to start at quarterback.

Now, fans know the Wolverine they have under center, and it's no secret that he's one of the most explosive players in the country.

That player, sophomore Denard Robinson, has undoubtedly been the focus of the Irish gameplan this week. But Notre Dame offers a challenge to the Michigan defense that could be just as potent as Shoelace.

Notre Dame junior receiver Michael Floyd is one of the premier wideouts in the country and terrorized Michigan's secondary last year. He tallied seven catches for 131 yards and a touchdown, before going down with an injury that derailed his season.

Containing him this year won't be any easier.

"It's going to be a huge challenge," Michigan coach Rich Rodriguez said during a teleconference on Wednesday. "He's so dangerous, particularly on those deep balls. He's got the size and ability to go up and get those, even when he's covered. That's what he did against us last year and he's done it against everybody he's played against, really."

Floyd presents a significant test in the passing game, but the Irish running game is arguably even more dangerous.

Notre Dame boasts a loaded backfield, with senior Armando Allen, who got the majority of the carries during the game against Purdue last weekend. He shared snaps with talented sophomore Cierre Wood, who didn't play his freshman year but was one of the nation's top running back recruits out of high school.

"Who's got us concerned are the running backs," Rodriguez said. "They are very elusive and very quick but run with a lot of power."

For the first time in a few years, the Wolverines will go into their game against Notre Dame with a much more confident situation at quarterback than the Irish. Notre Dame signal-caller Dayne Crist saw his first significant game action on Saturday and is playing on a surgically-repaired knee. Still, he looked solid in his starting debut, completing 19 of 26 passes for 205 yards and a touchdown.

The matchups on the field will be fun to watch, but it will be the matchup on the sidelines could be even more interesting. First-year Notre Dame coach Brian Kelly has followed a very similar path to the pinnacle of college football coaching as Rodriguez. Both started as head coaches of small schools, both are spread offense pioneers, and both now find themselves at the very top of their professions.

"He had great success at Grand Valley (State University) and everywhere he's been," Rodriguez said. "And I've been fortunate enough to have started the same way. Sometimes when you're at the smaller level you have to be more creative ... Now we're both at great institutions that have great tradition, great fan following and great interest."

Kelly runs a pass-oriented spread, while the Rodriguez spread is more run-oriented. Both coaches used to coach in the Big East and did play against each other once — Rodriguez's West Virginia team beat Kelly's Cincinnati Bearcats 28-23 in 2007.

"I've kind of followed his path, so to speak, what he's done in the last couple years," Rodriguez said. "And I've got a lot of respect for his ability to coach and build a program."

INJURY NOTES: While redshirt sophomore wide receiver Roy Roundtree is listed as probable, freshman spur Carvin Johnson will be out tomorrow with a sprained knee. Redshirt junior wide receiver Junior Hemingway is listed as doubtful.