Dirrell and his younger brother Anthony began boxing while still in elementary school in their hometown of Flint, Michigan.

A southpaw possessing exceptional athleticism and the ability to switch-hit, he was considered among boxing's top young prospects following an extensive amateur career.

Dirrell defeated future world title challenger Curtis Stevens on HBO's Boxing After Dark in June 2007.

[11] Thirteen months after that, Dirrell made a return to the ring with a unanimous decision win against Michael Gbenga after knocking him down in round 9.

Eighteen months after the Gbenga fight, Dirrell returned to score a fifth-round KO against Vladine Biosse.

DeGale gained two knockdowns in the second round, which proved to be the difference as he won a unanimous decision over Dirrell to win a 168-pound world title.

After the fight was stopped, Dirrell's trainer and uncle Leon Lawson approached Uzcategui and sucker-punched him before fleeing the scene.

Dirrell finished his opponent early, by dropping him three times in the third round, forcing the referee to stop the fight.