Liam Smith says the loser of his highly-anticipated rematch with Chris Eubank Jr at the AO Arena in Manchester on September 2 should retire.
Smith stopped Eubank Jnr early in the fourth round when the middleweight pair met in January, but he has revealed he will stop fighting after his next loss.
The Liverpudlian also suggested that 33-year-old Eubank should hang up his gloves if he is defeated, but joked his rival's ego would stop him from walking away from the sport.
Speaking to Sky Sports, Smith, who turns 35 next week, said: "Defeat is not an option. I've said in the past, my next loss will probably be my last one so there's your answer.
"He's come off the back of a stoppage loss. I probably predict he'll come off another stoppage loss too and then it's down to Chris and his team but at 33 years of age losing twice to me is his ambitions to still be world champion quite realistic? Probably not.
"I feel he would probably be done after this but with Chris and his ego, he might not be."
The rematch, which will be live on Sky Sports Box Office, will happen at the third time of asking after injuries to Smith saw the fight postponed twice during the summer. But Smith is confident he is now fully fit.
He said: "I'm fully healed and I'm back in the gym full-time. September 2 is not too far away and I'm looking forward to it and I've said it before, I'm looking forward to scratching that itch.
"I do everything right in the gym. I'm a better fighter than Chris Eubank Jr. I've proven it last time and I'll prove it again."
For Eubank Jr, a shot at redemption beckons and another defining night in his career after his title aspirations were dealt a major blow in their initial meeting, which he felt was stopped too early.
Smith responded by saying: "That's just typical Chris. I think Chris is the only man including his own team who believe the referee was at fault for that stoppage. I think the fight could have been stopped on the first knockdown and nobody would have had any complaints.
"Because Chris activated the rematch clause, he has to come up with some sort of explanation for the first fight.
"He's got a point to prove to a lot of people and he's got a point to prove to himself because he's got to change the outcome of the first fight but I'm massively confident it will be the same outcome again as long as the Liam Smith of old turns up.
Smith revealed his back injury is the only thing stopping him from turning up for the rematch at the AO Arena in September.
"As long as I'm healed I've got a good team around me who make sure I've trained properly. They make sure I'm on it," he said.
Smith recalled his controversial points defeat to Magomed Kurbanov in Russia two years ago as a huge setback but he still harbours hopes of becoming a world champion again.
He added: "Probably since I had that defeat in Russia, which was probably not meant to be a defeat I thought 'my next loss will be my last' and [particularly] at the age I'm at. I have ambitions of being world champion again and losing to somebody along the way, which isn't for a world title, it makes a world title a million miles away so I'm just going to concentrate on myself."
Watch Smith vs Eubank II live on Sky Sports Box Office on September 2. Tickets go on sale on Tuesday July 25. Sign up at Boxxer.com for exclusive access.