Promoter Eddie Hearn admits Jamie McDonnell faces his toughest fight yet against Naoya Inoue -- but hopes his height advantage will be decisive in Tokyo on Friday.
WBA bantamweight champion McDonnell has a five-inch height advantage over Inoue that Hearn in the world title fight that is being streamed live on ESPN+ on Friday and is due to start 1.15pm U.K. time.
Hearn is confident of McDonnell upsetting the odds and conquering a fighter known as 'Monster' who has stopped 13 of his 15 victims.
"You can see how popular Inoue is over here and it's easily the most difficult fight of Jamie's career," Hearn told ESPN from Japan.
"The weight is always an issue but they said it was not quite as difficult as his last fight which is good news and it's always difficult making weight away from home.
"I don't see the weight being a major factor in this fight, but the height is massive. He was huge compared to Inoue at the weigh-in and he has to use that to his advantage.
"Inoue looked very full at the weight and looked as though he could take three pounds off easy, so he's a small bantamweight and Jamie is a big bantamweight and that has to be an advantage. But it comes down to how Jamie uses it."
Inoue (15-0, 13 KOs), 25, is aiming to become a three-weight world champion against McDonnell (29-2-1, 13 KOs), in front of his home fans at the Ota-City General Gymnasium in Tokyo, Japan.
McDonnell, 32, will be making a seventh defence of his WBA "regular" bantamweight belt (Belfast's Ryan Burnett holds the full title) and has experience of winning overseas which Hearn hopes bodes well for him.
McDonnell, from Doncaster, has title wins over the likes of Japan's Tomoki Kameda and Venezuela's Liborio Solis in America and Monaco respectively.
"Jamie seems to be immune about fighting away from home because he has travelled to win the European title and Kameda twice in America and fought in Monte Carlo also," Hearn said.
"It's very different out here and very different from Doncaster but Jamie has not been beaten for ten years and he has won away before.
"This would be one of the biggest British wins for a boxer away from home."
McDonnell-Inoue will air live on ESPN+ in the United States beginning at 8:15 a.m. (1.15pm U.K.) ET on Friday.