Heisman Trophy finalist Tyrann Mathieu was kicked off LSU's football team Friday for breaking an athletic department rule, a blow to the Tigers' national championship hopes three weeks before their season opener.

The junior defensive back - nicknamed Honey Badger for his tenacious style, small stature (5-foot-9, 175 pounds) and blonde streak of hair - rose from obscurity to become one of college football's biggest stars last season.

He was a sleeper Heisman candidate as the Tigers won the Southeastern Conference championship and reached the BCS title game. But almost as quickly as Mathieu rose to fame and became the face of LSU football, the Honey Badger phenomenon ended in Death Valley.

"We'll miss the guy," coach Les Miles said at a news conference. "The football team's got to go on. We'll have to fill the void."

Miles would not specify the reason Mathieu was dismissed. His Tigers are still among the favorites to win the national title this year, even without Mathieu.

Athletic Director Joe Alleva said Mathieu, who was suspended for a game in 2011 after failing a drug test, violated an athletic department rule and had his scholarship revoked.

The Times-Picayune of New Orleans, citing an unidentified person close to the player, reported that Mathieu failed another drug test. Several high-ranking LSU administrators said they either did not know which rule Mathieu had violated or refused to discuss the matter. School policy allows for a player to lose his scholarship even without another positive test if he does not fulfill all the terms of university probation.

- Associated Press