Lewan, a former Michigan offensive tackle, was accused of hitting the fan, hours after the Buckeyes beat the Wolverines in Ann Arbor last season, 42-41. He was originally charged with aggravated assault and assault and battery.
Lewan, 23, instead pleaded guilty to two misdemeanors and agreed to pay $1,714 in restitution, mostly medical bills. He said his brother was involved in a "confrontation" and he joined the angry crowd.
"I had been drinking. I was intoxicated," Lewan told the judge.
Assistant prosecutor Brenda Taylor identified the victim as Ryan Munsch.
Lewan and his lawyer, John Shea, declined to comment after the hearing. District Court Judge Elizabeth Pollard Hines set a Dec. 15 sentencing date.
The 6-foot-7 Lewan has started the past three games for the Titans, who have a bye week this weekend.
Lewan initially told police that he was only separating people but later acknowledged he "could have pushed someone," according to a police report about the Dec. 1 incident.
"He knocked the guy to the ground and he punched him," a witness, Alexandra Dileo, told police, according to the report.
Copyright 2014 by The Associated Press