Wladimir Klitschko believes old rival Anthony Joshua can “overcome the challenge” of defeat to regain a world heavyweight title.

Joshua lost his IBF, WBA and WBO belts to Oleksandr Usyk last weekend, which was a major blow to his hopes of facing WBC champion Tyson Fury in an undisputed title fight.

“We have seen AJ challenged,” said his former opponent Klitschko.

“I remember my time. I lost two fights within [13 months in 2003 and 2004].

“To bounce back? To eventually become one of the longest reigning champions?

“AJ can still have his time, absolutely. It is all about how to overcome the challenge.”

Klitschko first lost to Ross Purrity in 1998, but became a world champion until he was shockingly stopped by Corrie Sanders, and again by Lamon Brewster.

He then went undefeated for the next 11 years, reinventing his style and ferociously keeping the IBF, WBA and WBO titles while his brother Vitali held the WBC belt.

Klitschko’s reign was ended by Tyson Fury in 2015 before he was beaten by Joshua in their sensational Wembley Stadium classic.

He retired with 64 wins and five losses as the greatest heavyweight of his generation.

Klitschko said about his fellow Ukrainian who beat Joshua: “Usyk made history.

“Since 2012, I watched Usyk winning his gold and I watched AJ winning his gold.

“Usyk has been undefeated for such a long time, winning all the titles as a cruiserweight and now with the heavyweights.

“This man is something special.”

Usyk is only missing Fury’s WBC belt to emulate his own achievement of becoming the undisputed champion at cruiserweight.

Joshua said in the aftermath of losing his titles: “I’ve watched the fight, analysed my preparations and identified my mistakes. I’ve learnt my lesson.

“Don’t worry about me. My spirit is strong!”

Fury gave advice to Joshua for the rematch with Usyk: “There are no secrets, no rocket science, to boxing.

“Fighters today make it technical. This is just two men punching each other for 12 rounds or less.

“Go to bed early, eat right, drink plenty of water, and get stuck in! If it’s not going your way with the game-plan that you’ve got? Change it up!

“Give your best, give all that you can, leave it all in the ring. Don’t say ‘should have’, ‘would have’, ‘could have’.

“Don’t think: ‘If I trained harder, I could have done better’.

“My advice to Joshua is; get stuck in the best way he knows how! Put your best foot forward. Swing away, swing away!”

Fury added about Joshua: “I’ve got no interest in slating anybody or kicking anybody while they are down,” Fury said. “It’s not my style.

“I like to pick on people who are doing well, who are successful, on top of their game.

“I don’t like picking on people who are down, probably at their lowest point, and probably mentally unstable after a loss after a long reign.”

Fury defends his WBC title against Deontay Wilder on October 9 in Las Vegas.

Watch Chris Eubank Jr vs Anatoli Muratov on Saturday night, from 7.30pm on Sky Sports.