Tyson Fury and Deontay Wilder see the threat posed by Oleksandr Usyk differently, but Anthony Joshua has warned: "I fear none of them."
Joshua is set to defend his IBF, WBA and WBO titles against Usyk in September at the Tottenham Hotspur Stadium in London while Fury and Wilder meet in a WBC title fight in Las Vegas on July 24 in a pair of world heavyweight championship collisions.
Joshua and Fury's dream undisputed title fight could be rectified for later this year if they emerge with their belts intact.
Fury exclusively told Sky Sports, when asked if Usyk will trouble Joshua: "I don't think so, no. Usyk lost to Derek Chisora in my opinion, and Derek is 10 years past his best.
"He's a cruiserweight who would be knocked out by Wilder in one round."
But Wilder exclusively told Sky Sports about Usyk's chances of beating Joshua: "Everyone is a threat until proven otherwise. Every fight is dangerous - you never know what night a person will have."
Malik Scott, Wilder's new trainer, added: "Usyk is a dangerous fight for anybody, not just Joshua.
"You have to commend Joshua for taking him on. Usyk is not a guy everybody is trying to fight - he is a guy that people would prefer not to fight.
"Usyk is learning on the job against the most dangerous guys.
"He didn't go on a seven-fight plan. This is his third fight at heavyweight. That's a big climb.
"It will be interesting how Usyk responds to Joshua's size and technicalities, and how Joshua responds to Usyk's speed as a southpaw."
Usyk is undefeated and has won the World Boxing Super Series and undisputed title in the cruiserweight division. He and Joshua both took gold medals home from the 2012 Olympics.
Joshua exclusively told Sky Sports when asked what dangers Usyk poses: "None. I fear none of them.
"He doesn't bring anything that I haven't seen before.
"Two arms, two legs, a brain and a bit of heart. That's it, so let's get it on.
"He's a good fighter. I'm challenging myself in training - it's not so much his challenge.
"I will go in there not thinking about the task ahead. That's something I can't do. I don't want to overcomplicate this task.
"I will believe in myself, go in there and do what I know I can do.
"People don't know what I can do until they are in the ring with me.
"I'll show what I'm about. I will tick another box when the final bell goes - if it does go!"
Joshua has been forced to refocus his attention on Usyk after initially expecting to fight Fury.
He has brought in Ireland's Thomas Carty as a sparring partner to replicate Usyk's southpaw style.
"A change of opponent with a completely different style," said Joshua.
"I was at the final destination on the road to undisputed but now there's another pitstop.
"I will take on the former undisputed cruiserweight champion of the world who has moved up to heavyweight."