Promoter Eddie Hearn says Anthony Joshua should be ready for his “toughest ever fight” when he enters the ring against Oleksandr Usyk in London on Saturday night.
The British world heavyweight champion defends the WBA, IBF and WBO titles against Usyk at the Tottenham Hotspur Stadium knowing that any potential unification fight with Tyson Fury is under threat should he fall short this weekend.
Joshua, 31, has height and reach advantages and will almost certainly be heavier but Hearn admitted he was nervous ahead of the bout.
“This is probably AJ's toughest-ever fight and I think he's going to prove to the world how good he is,” Hearn told the PA news agency. “He's ready for this fight but it's the ultimate challenge with someone that's very strong mentally.
“Mentally, it will be draining [for Joshua] because he's going to have to think a lot, there will be a lot of feints from both men and reactions are going to be key.
“I just can't wait to watch it unfold. It's a real, real high-end heavyweight fight. [Usyk is] going to be a tough, tough nut to crack. AJ's got to break him down, beat him up and hopefully take him out.”
The 34-year-old Ukrainian, a former undisputed cruiserweight world champion, won heavyweight gold at the London 2012 Olympics while Joshua triumphed in the super-heavyweight division.
Despite the potential threat in front of him, Hearn has been impressed by Joshua's confident demeanour in the build-up the fight, expected to draw a crowd of more than 60,000.
“I've never seen him so assured about a fight, which is ironic because technically this is his toughest fight,” said the promoter. “He knows how tough this fight is, he wants to prove to the world that he's the best heavyweight in the world.”
It is hoped that if both Joshua and Fury, who fights Wilder for a third time on October 9, come through their respective latest tests then a mouthwatering clash between the two compatriots can be arranged next year.
Hearn, though, said: “Do you know what? At the moment it’s the last thing on my mind because all I care about is winning on Saturday.”