Here, the PA news agency takes a look back at the fight.
After Carl Froch vacated the IBF super-middleweight title due to injury, challengers DeGale and Dirrell were paired together. The bout took place at the Agganis Arena in Boston and DeGale put on the performance of his career, completely outboxing the American. He floored Dirrell twice in the second round, but could not force a knockout. However, the Briton had done enough to earn a comfortable unanimous points victory, with two judges scoring the fight 114–112 and the third 117–109.
Olympic gold to world champion
In beating Dirrell and becoming world champion, DeGale earned a slice of history. He became the first British boxer to win an Olympic gold as an amateur and then win a world title as a professional. The Londoner topped the podium at the 2008 Beijing Games. Only Anthony Joshua and Nicola Adams, have followed suit.
What happened next?
DeGale took on Sweden's Badou Jack in a unification fight, but it was declared a draw so he retained his IBF belt. But he lost it in his next defence against Caleb Truax at London's Copper Box on a majority decision only to claim it back in a rematch five months later with a unanimous points decision. A routine knockout victory over Fidel Munoz followed before DeGale's career ended in 2019 when he was beaten on points by Chris Eubank Jr and subsequently retired.