During the 2003 season, the senior led the team in tackles, with 117, adding 1 forced fumbles, 2 interceptions, and 19 tackles for loss. Lehman closed out his college career in the 21-14 Sugar Bowl loss against the LSU Tigers with eight tackles (six solo) and two stops behind the line of scrimmage, including one sack. He was recognized as a unanimous first-team All-American and a first-team All-Big 12 selection. He was awarded the Dick Butkus Award, given to the nation's top linebacker, as well as the Chuck Bednarik Award, given to the nation's top defensive player. Lehman was rated the top outside linebacker pro prospect in the country by The NFL Draft Report.