James DeGale will not and should not retire after his shock defeat and subsequent loss of his IBF super-middleweight title to the American Caleb Truax on Saturday night, the fight’s promoter has insisted. Frank Warren also expressed his desire to organise a rematch between the pair in the new year.

DeGale was expected to comfortably beat Truax in the 31-year-old’s fourth defence of the belt he secured by beating another American, Andre Dirrell, in 2015. However, after delivering a lacklustre showing in front of a near sell-out crowd in east London, the Olympic gold medallist was deservedly beaten and dethroned via a majority points decision. The ringside judges scored the contest 114-114, 115-112, 116-112.

DeGale had hoped to use his first fight in 11 months – and his first on these shores in three years – as a springboard to unify the division, starting off with a meeting with the WBC champion David Benavidez in the spring followed by a rematch with the WBA title holder and his long-term rival George Groves. But those plans must now be shelved, with Groves loth to face the man he defeated in May 2011, judging by the tweet he posted immediately after Saturday’s bout. “Call it a day, mate, you ain’t got it no more,” the 29-year-old wrote.

DeGale seemed severely troubled against Truax by the shoulder he damaged in his draw with Badou Jack in January, and which required surgery in the summer, and there were suggestions after the 26th fight and second defeat of his professional career that he should consider retiring. That was dismissed by Warren. “I don’t think he [DeGale] will retire, he’s just had a bad day at the office,” the promoter said.

“It’s not like he’s a washed-up fighter, he’s a young man, he’s not had a lot of fights. It’s a setback, any loss is a setback. He’s lost his title but champions come back – I’ve seen it loads of times. I’ve seen Nigel Benn come back and win his title, [Chris] Eubank, lots of guys. It’s all about coming back and regaining them.”

Warren said he did not know if DeGale had agreed to a rematch clause with Truax before their clash but said he would discuss that with the fighter’s adviser, Al Haymon. He also said that any rematch would definitely take place in Britain given Truax’s lack of profile in the US. The 34-year-old from Minnesota arrived in the UK with a 28-3-2 record, with no high-profile wins.

“It’s a big upset, no doubt about it, but you’ve got to take into consideration James’s shoulder – the punches weren’t flowing,” Warren said. “But it held up for the 12 rounds so now what we’ve got to do is get Christmas out of the way and try hard to make the rematch for the spring.

“He [DeGale] could have won the fight but he let the other guy win by letting him come forward. He got his tactics wrong. When he was on the ropes he wasn’t letting his shots go, it was single shots. I wanted to see him use his jabs more, he’s got a really authoritative jab.”

DeGale was taken to hospital immediately after the fight on Saturday to have his nose checked after it was broken by Truax during an explosive fifth round. It is not thought to be a serious injury, with the fighter more concerned with his right shoulder following a contest that left his professional record standing at 23-2-1.

“The shoulder, I had serious reconstruction,” DeGale said. “There’s no pain but I’ll have to go back, have a look and see. I’m going to speak to Al Haymon. Maybe I can get a rematch.”