He played college football for the Illinois Fighting Illini, earning consensus All-American honors in 2007.

He was signed by the Minnesota Vikings as an undrafted free agent in 2008, and was also a member of the Oakland Raiders, Carolina Panthers, Philadelphia Eagles, and San Diego Chargers.

During his senior year, he tallied 191 tackles and was named to the prestigious Illinois High School Football Coaches Association All-State Team.

During the 2007 campaign, Leman led the Illini to nine wins and helped the team earn a trip to the Rose Bowl.

[citation needed] Leman stands at sixth place on Illinois' all time tackle list.

His 152 tackles in the 2006 season ranked first in the Big Ten and is the sixth best single-season effort ever posted by an Illini gridder.