Andre Ward defeated Carl Froch in the Super Six super-middleweight final despite breaking his hand in two places.
The American injured his hand in training but battled on to add the WBC belt to his WBA crown with a one-sided points win on December 17.
"We had to go through with the fight," Ward told ESPN.
"I was extremely concerned the whole week of the fight, but I knew I couldn't pull out.
"Early on the adrenaline was working. But in the sixth round, when I hit him on top of the head, that is when I really hit a wall in terms of the pain. But I had no choice. We got through it."
Promoter Dan Goossen confirmed that Ward suffered a double fracture before the fight.
