Eddie Hearn insists that Darren Barker believes he can overcome the odds and shock Sergio Martinez on October 1.
The unbeaten European middleweight champion will take a huge step up in class when he faces the veteran Argentine for the WBC middleweight title.
Martinez, who holds recent victories over the likes of Paul Williams and Kelly Pavlik, will be the massive favourite to retain his world title at an American venue that is yet to be confirmed.
But Barker's promoter Hearn is confident the Londoner will put up a good fight and says Barker thinks he can cause a major upset.
"Darren's 29 and when the chance comes at his age you have to take it," Hearn told The Sun.
"He's a huge underdog but Darren thinks he can win. He won't disgrace himself."