Defeat for AJ would be "unthinkable"
Former cruiserweight world champion Johnny Nelson believes a defeat for Anthony Joshua against Oleksandr Usyk would be a shock but acknowledges he is facing his "best" opponent to date.
The Ukrainian is the mandatory challenger for Joshua's WBO belt and can be backed at 3.00 to win, with AJ available at 1.40.
AJ enters the ring for first time in 2021
It will be Joshua's first outing since December when he knocked out Bulgarian challenger Kubrat Pulev to retain his WBA, IBF, and WBO belts.
A bout with Tyson Fury continues to be in the works but with the Manchester-born fighter preparing for his third fight against Deontay Wilder, Joshua will now face the undefeated Usyk at the Tottenham Hotspur Stadium on Saturday night.
Usyk is the best fighter we may have seen in the ring with AJ to date.Johnny Nelson
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The 34-year-old has spent most of his career at cruiserweight and unified every world title but, following a blistering knockout win against Tony Bellew in November 2018, declared his intention to jump up to heavyweight class.
Usyk unbeaten since stepping up
He has breezed through his two fights against Chazz Witherspoon and Derek Chisora but now faces a step up in class.
Joshua, who has only ever lost one fight - being shocked by Andy Ruiz at Madison Square Gardens in June 2019 - is expected to make a statement as he aims to retain his belts.
However, Nelson has warned him not to be complacent against the brilliant Usyk.
"Usyk is the best fighter we may have seen in the ring with AJ to date," he said. "Not everyone will realise that. People might think, 'AJ is getting in the ring with a cruiserweight,' but he is the best, in my opinion. He's just a winner all the way through."
On a potential second career loss for Joshua, Nelson added: "I think it's possible for AJ to come back from a shock, but it's unthinkable."