Anthony Joshua faces the biggest test of his career when he fights Wladimir Klitschko in a heavyweight clash of the titans, according to trainer Peter Fury.
IBF champion Joshua meets 68-fight veteran Klitschko, live on Sky Sports Box Office, in front of a record-breaking 90,000 sell-out crowd at Wembley Stadium on April 29.
Klitschko has already been inactive for more than 14 months since losing his WBO, WBA 'super' and IBF titles after being outpointed by Tyson Fury in Dusseldorf in November, 2015.
The Ukrainian's response to his first loss in more than 11 years will be key to the outcome of his clash with Joshua, according to Tyson's uncle and trainer Peter, who says Klitschko's experience gives him a slight edge over the 2012 Olympic gold medallist.
"I think this is the acid test for Anthony Joshua and if he comes through it he deserves maximum credit," Peter Fury told Sky Sports.
"If Klitschko is hungry, on cue, and really wants those belts back it's going to be one hell of a fight.
"I'd have to slightly favour Klitschko because he has the experience but the question is whether Klitschko really has the desire to put his body through it all again, especially with the inactivity after being beaten by Tyson.
"It all depends on what sort of Klitschko turns up on the night, but if we get a 100 per cent Klitschko then I think Joshua will have problems."
Klitschko, who turns 41 a month prior to the April showdown, told Sky Sports News HQ last month he intends to bring the frustration accumulated through inactivity to the ring for his clash with Joshua.
But Fury insists Klitschko's ring absence raises serious questions about his psychological and physical capabilities to compete against a fighter of unbeaten Joshua's calibre.
He added: "Just what is going on up there [in Klitschko's head] we don't know, because it's all in the mind isn't it?
"We just don't know if Wladimir will be hungry. He could be more hungry now than ever, or, after being inactive for so long, he could be coming back for the money, for one last pay cheque.
"He's almost 41. Is the desire there anymore? These are questions we won't know the answer to until that bell goes.
"But whether Wladimir is over the hill or not won't be AJ's fault. You can only fight what is put in front of you and Klitschko will be by far the biggest test of his career."
Watch Anthony Joshua vs Wladimir Klitschko from Wembley Stadium, live on Sky Sports Box Office on Saturday, April 29.