The Olympic gold medallist and former IBF super-middleweight champion demonstrated further signs of decline as he lost for the third time as a professional, and against an opponent he would have expected to convincingly outbox at his peak.
For all that the 29-year-old Eubank Jr has improved, perhaps partly owing to recruiting the previously little-known Nate Vasquez as his trainer, DeGale again struggled to convince throughout a fight he had previously said would leave the loser with little choice but to retire.
There are a few lucrative options left for him to pursue — unlike his rival, who has revived his career with his finest ever victory — and having become Britain’s first Olympic gold medallist to win a professional world title, he insisted he had “made his mark”.
After his unanimous decision defeat, via scores of 114-112, 115-112 and 117-109, the 33-year-old DeGale said: “I’ve left my mark in boxing. Olympic gold, two world titles, but Chris performed well. I just didn’t do enough but when you’re in there with wild punches.
“I’m going to have to go back and watch it. I just didn’t do enough.
“I just didn’t do enough. I’m going to go back, talk to my team, my family, but I’m pretty sure. I’ve been to the heights in boxing, I’m the history man; if I call it a day now, that’s nice.”
Eubank Jnr, who is expected to pursue a rematch with Billy Joe Saunders, given his rival is also moving into the super-middleweight division, said: “I’m coming for all the other belts in the super-middleweight or the middleweight division.
“I knew that he was gonna come in there and run. He’s a very slick southpaw. But the game-plan worked. Smart pressure.
“I dominated pretty much every single round. People said I was gonna have my head jabbed off; I proved those guys wrong.
“I’m back on top. This is one of those fights which puts me in a position to challenge for world titles and I’m very happy.
“There was massive pressure. We were both on the edge of this cliff and someone was going to fall, and whoever falls can’t come back. I’m still here now, onwards and upwards.”