Iowa's Adam Robinson (32) gets wrapped up Michigan State's Johnny Adams (5) during the second half of their Big Ten Conference college football game Saturday, Oct. 30, 2010 at Kinnick Stadium in Iowa City. (Brian Ray/The Gazette)

IOWA CITY — Iowa running back Adam Robinson suffered a mild concussion late in the Hawkeyes’ victory over Michigan State, according to sources. His availability for Saturday’s game at Indiana is 50-50.

Robinson, the No. 3 rusher in the Big Ten, didn’t practice Tuesday, according to sources. He continues to be monitored.

On his radio show last night, Coach Kirk Ferentz would neither confirm nor deny Robinson’s status.

Robinson carried the ball twice in the fourth quarter and rushed 20 times for 69 yards against MSU. Robinson leads the Hawkeyes with 806 yards on a Big Ten-leading 172 carries.

Freshman Marcus Coker saw his first action since Week 4 and carried 16 times Saturday for 40 yards.

“He’s earned that (playing time) and he’s worked hard in practice and I think he’s caught up now from that injury (broken collarbone in camp),” Ferentz said after the MSU game. “We’re going to have to find a way to spell Adam.

“Adam continues to play really well. He just does a great job. But to play in a schedule, in a conference like we are in and a schedule like we have, we are going to need more than one guy.”

Coker, a 6-foot, 230-pounder, rushed for 1,698 yards and 23 TDs last season at DeMatha Catholic High School in Maryland.

After Coker, red-shirt freshman Brad Rogers would be the next running back. Rogers is also the No. 2 fullback.

It’s unclear whether senior Paki O’Meara would be an option at running back. He’s seen limited special teams action since suffering a concussion at Arizona.