Kubrat Pulev says he will fulfil his "destiny" by beating Anthony Joshua to become world heavyweight champion at Tottenham Hotspur Stadium on 20 June.
The Bulgarian, 38, is mandatory challenger in what is Joshua's first bout in the UK since 2018 and has vowed to take the IBF, WBO and WBA titles.
The 5 Live Boxing team likened the bout to a "semi-final" as a win could see Joshua face WBC champion Tyson Fury.
"What needs to be added is Pulev will go for it," said 5 Live's Steve Bunce.
"He has to, because Andy Ruiz Jr went for it and he beat Joshua. There will always be a question now over Joshua. Pulev will be in the 'Joshua's got nothing' camp.
"Pulev will be getting in the ring with the people around him whispering in his ear about how easy it is going to be to beat that guy."
Un-fancied Pulev on a mission
Pulev's promoter Bob Arum is adamant his fighter will knock out Joshua, who is a 1-10 favourite with some bookmakers.
In his Las Vegas office, he recently told the BBC Sport boxing team that if Ruiz could stop the Briton - as he did in June before losing a rematch - then Pulev will do the same.
Such a result would give Arum control of all four heavyweight belts as he also promotes Fury, who will put his WBC title on the line in a third fight against Deontay Wilder - scheduled for 18 July.
Many boxing fans are keen to see Joshua and Fury meet for all four belts but both would need to win before complex negotiations take place over any bout.
Pulev, who has one defeat in his career - against Wladimir Klitschko in 2014 - believes he will wreck such plans.
"Becoming a heavyweight world champion has always been my mission in life and on 20 June 2020 I will fulfil my destiny," Pulev said.
'The biggest year of AJ's career'
Joshua made no reference to Fury or Pulev in his comments on the fight saying only that he was keen to make "history" in what is the first boxing bout at the new home of Tottenham Hotspur.
"The belts go back up in the air and nothing will stop me from being victorious," said Joshua, 30.
His promoter Eddie Hearn has spoken about Joshua and Fury meeting in December should they both win.
That contest would probably take place in Saudi Arabia given the weather in the UK late in the year would make any stadium bout unlikely, while arenas in Britain would not offer the capacity needed.
A host of other issues would need to be worked out too - such as how rival television networks and promoters could work together - but a defeat for Joshua against Pulev would end hope of any Fury fight in the short term.
"As we go into what I believe will be the biggest year of AJ's career so far, all our attention turns to Pulev in an absolute must-win fight," said Hearn.
"Pulev is undefeated in six years and his team, and especially Bob Arum, really fancy this. I think you are going to see something special from AJ - a destructive performance on the road to undisputed."
'Pulev is close to elite'
Joshua recovered from his shock loss to Ruiz by out-boxing the Mexican in Saudi Arabia in December for a wide points win.
He was praised for the display, though some pointed to Ruiz's weight gain as a contributing factor and others felt Joshua - floored four times when he first met Ruiz - looked uneasy again whenever his rival got close to him in the rematch.
Pulev was due to face Joshua in 2017 but withdrew with an injury and has reeled off eight wins since his loss to Klitschko in 2014.
"Pulev hurt Klitschko in the first round and hurt him with the jab," said 5 Live Boxing's Mike Costello.
"He did have a go. He's beaten Hughie Fury and Derek Chisora which is a sign he belongs close to the elite. For me he is just below that elite rung.
"Joshua can re-establish himself and in the end he just has to win. Then we get on that bandwagon for a fight with Fury later in the year. I am thinking the same December weekend as when Joshua fought Ruiz and, again, in Saudi Arabia."
Bunce added: "It is the well that never runs dry. Rematches, grudge fights, overdue fights, outdoor stadiums, indoor stadiums, sell-outs, Las Vegas, Tottenham, the world. That's the heavyweight scene right now."