Martin Murray says defeat to Gabriel Rosado will mean it is time to hang up his gloves.
The pair will meet in a bill-topping battle at Liverpool's Echo Arena on April 22, with Murray - who has unsuccessfully challenged for a world title on four occasions - able to propel himself back up the rankings with victory over his American opponent.
Murray's last shot at a belt came in his WBA International super middleweight title defeat to George Groves in June last year, and losing to Rosado would be the final straw for the 34-year-old.
"Obviously I've been fighting at super middleweight and this is back down at middleweight so I've had to come back down there but this is a must win for me," said the St Helens fighter.
"I know I kept saying Groves was a must win but I've decided to go on and this really now is a must-win fight. If I can't beat him Rosado I think it's time to hang the gloves up.
"The motivation for this fight compared to the last fight, the fight after Groves - I've never had more motivation than I've got now so obviously I've started this year really excited.
"The fact this fight is here in Liverpool I'm chomping at the bit."
Murray, who was speaking before David Haye and Tony Bellew's press conference, also offered his prediction on their big fight on Saturday.
"Bellew's my man, I'm not going to back against him," Murray said.
"People are writing him off and don't think he'll have a chance but Tony has got the power and can beat anybody on his night. I truly believe he's going to do it.
"He fought the top guys at light-heavy, has gone to cruiser and won a world title and now he's going up to heavy.
"He fought all the top guys and he's world class but I just think he's got the power to do it. He's got inside David Haye's head and is playing the game perfectly."
