COLUMBIA — Preparing to face Michigan quarterback Denard Robinson was often challenging for opposing defenses over the past four seasons, primarily because of his unpredictability.

Robinson dazzled fans immediately upon his arrival in Ann Arbor in 2009. He ran for a 43-yard touchdown on his first college snap. He introduced college football to his delightfully unique nickname, Shoelace, and made everybody wonder just how in the world someone could dart around the field so fast with the shoelaces of his cleats untied.

By the beginning of his sophomore season, he was mentioned as a Heisman Trophy front-runner.

That never materialized, as he has thrown 35 interceptions since the start of that season, compared with 47 touchdowns.

But he remained just as frustrating for defensive coordinators to stop as he was fascinating for everyone else to watch.

While his passing numbers haven’t been great since that Heisman chatter began before the 2010 season, and his completion percentage dipped from 62.5 that year to 55 and 53.6 the next two seasons, he still has 37 rushing touchdowns over that span to go with 4,044 rushing yards and 6,062 passing yards.

The end of his senior season was complicated by an injury to his throwing elbow on Oct. 27 against Nebraska. He missed the next two games and didn’t throw a pass in the following two.

Yet as he concludes his career in Tuesday’s Outback Bowl against South Carolina, he is still unpredictable. USC’s coaches can’t be sure of how much his elbow has healed and how much he might throw in the game. Or perhaps Michigan’s coaches will stick with Devin Gardner as their quarterback and use Robinson in a running back/wide receiver role that he played in the final two games.

He is most effective out of the backfield, running zone read plays as a quarterback or lining up as a traditional running back. Michigan’s tailback, Fitzgerald Toussaint, suffered a serious leg injury Nov. 17 against Iowa and is out for the season. That was also the game in which Robinson caught the only two passes of his career. So he is much less proven as a receiver than a runner.

Regardless of all the pain and uncertainty Robinson faced over the past two months, his speed and dodging ability are still major assets for Michigan. Few USC players know that better than cornerback Akeem Auguste, who grew up in Hollywood, Fla., and played high school ball against Robinson, who is from Deerfield Beach.

“I ain’t going to lie — he moves,” Auguste said. “But at the same time, we’ve got a lot of speed on our team, so we’re not really worried about it. We’re going to have something for him. As far as being out there at wide receiver, we’re really not expecting too much from him.”

USC defensive coordinator Lorenzo Ward said Michigan is more of a passing team with Gardner in the game, but Ward and the defensive coaches know there is the wild card of Robinson having all this time to rest his elbow.

“He’s the best athlete that we’ll play this year at quarterback,” said defensive line coach Brad Lawing. “If he’s healthy throwing the ball, that causes some problems and we know that. I know his arm has been hurt, but guys like him, you worry about them. You lay up awake every night and you worry about those guys because they can beat you.”

Michigan offensive coordinator Al Borges will obviously worry first and foremost about using Robinson to win the game. But if Robinson does capably catch passes or carry the ball as a hybrid back, it would impress NFL scouts who are wondering about his role as a pro.

Still, USC’s players are preparing for Robinson the passer, operating under the assumption that he has had enough time to recuperate. As with any scrambling quarterback, USC’s cornerbacks must avoid being drawn away from their receivers and toward the line of scrimmage at the first sign of a scramble.

“Once he starts scrambling, I have to find a (receiver) and match him,” said cornerback Victor Hampton. “I can’t really worry about what (Robinson) is doing until he gets way down the field.”

Of course, USC’s defensive line, impressive all season, can limit Robinson’s options by sealing his rush lanes, getting pressure off the edge and making him stay in the pocket.

“They have a lot of plays where he just runs around and finds open receivers,” said defensive tackle Kelcy Quarles. “That’s why it’s important for us to contain him in the pocket.”