DeGale had just one loss in his previous 23 bouts prior to this fight.
After holding on to his IBF belt following a bruising draw against Badou Jack in January, the Brit felt he had a point to prove.
DeGale edged the first couple of rounds, and came out switching to a southpaw stance.
The former Olympic gold medallist fired from the off, and produced a couple of heavy rights.
Truax soaked up the pressure and started to hit back in rounds three and four.
Although DeGale spent a significant amount of time on the ropes, there was little separating the two.
Truax’s belief continued to grow and he was on top in the latter rounds.
DeGale started to swing wildly trying to engineer the angles to land a sucker blow.
He tried to stand and trade to trade blows, and Truax almost seemed to posture as if he thought he had won the contest, much to the annoyance of the London CooperBox Arena crowd.
After his long time away from the ring, the result ultimately told.
One judge scored a fight a draw, while the other two scored it 115-112 and 116-112 in favour of Truax.