As a redshirt freshman, he was a backup cornerback, tallying 64 tackles, 3 interceptions, 11 passes defensed and 4 fumble recoveries.
As a sophomore he was named a starter at cornerback, registering 57 tackles, 3 interceptions, 13 passes defensed and 3 forced fumbles As a junior, he collected 55 tackles, 6 interceptions and 16 passes defensed, while having 26 punt returns for a 10.4-yard average and 11 kickoff returns for a 24.6-yard average.
[1] Mathis was signed as an undrafted free agent by the Dallas Cowboys after the 1997 NFL draft, after dropping because of his size and small college background.
He would end up making the team after taking advantage of Deion Sanders being away while playing professional baseball and displaying his track speed (4.19 seconds in the 40-yard dash).
He also established himself as one of the more productive kickoff returners in the league, averaging 24.8 yards to finish ranked sixth in the NFC.
The fight led to an NFL rules change where non-kickers cannot enter a neutral zone between the 45-yard-lines prior to the game.
On September 13, 2005, he was lost for the season with a career-threatening left knee injury, after tearing 3 ligaments during a practice drill.
[8] The next year, he returned to play but suffered a career-ending neck injury, while tackling Eddie Drummond on the opening kickoff against the Detroit Lions on November 5, 2006.