London - World heavyweight champion Anthony Joshua may have proclaimed himself "the best in the division" ahead of putting his titles on the line against Russia's Alexander Povetkin at Wembley Stadium but he also stressed a defeat would not signal the end of his career.
The 28-year-old British boxer has won all 21 of his fights since entering the paid ranks, with 20 by way of knockout, although his last title defence, against New Zealand's Joseph Parker in Cardiff in March, saw him go the distance for the first time as a professional before he secured a unanimous points decision.
But Joshua, citing the example of many great boxers, insisted a reverse in front of his home crowd on Saturday would not see him bow out of boxing.
"That fear of losing is always there," Joshua, the International Boxing Federation, World Boxing Association and World Boxing Organisation champion, told reporters at Wembley.
"Sugar Ray Robinson, the best fighter of all time, can lose. Sugar Ray Leonard, Marvin Hagler, Thomas Hearns, Roberto, Duran, Muhammad Ali, Mike Tyson, Evander Holyfield, (all lost).
"So who am I to go undefeated?...I have lost before as an amateur and that didn't deter me from getting where I am today," added the London 2012 Olympic champion.
When it was put to Joshua that losing would not end his career, he replied: "One hundred percent and I know that it could happen because I know how tough this sport is."
"That's what I say in boxing, there's no league one, league two...You are either the best or you're not."
Joshua has a significant height and reach advantage of several inches over Povetkin, the 2004 Olympic champion.
Friday's weigh-in also confirmed a significant size difference, with Joshua tipping the scales at 17 stone 8 pounds (111.5 kilogrammes) compared to the 39-year-old Povetkin's 15st 12lbs.
This fight sees Joshua returning to the scene of arguably his greatest triumph, an 11th-round stoppage of former champion Wladimir Klitschko last year.
Klitschko is the only man to have inflicted a blemish on Povetkin's 35-fight record, with a points win back in 2013.
Povetkin, however, served notice of his formidable punching power with a sickening knockout of Britain's David Price on the Joshua-Parker undercard at Cardiff's Principality Stadium.
Nevertheless, Joshua had no doubt his best would be good enough to defeat Povetkin.
"Yeah 100 percent," he said.
"I am the best in the division. There is no doubt about it. It's been proven. There hasn't been a time in boxing since I've been an amateur that I haven't been on top," added Joshua, whose management have yet to secure a heavyweight unification fight with World Boxing Council champion Deontay Wilder.- 'Well is deep' -
Joshua though insisted he was fully focused on the challenge posed by Povetkin.
"I'm up against one of the best fighters in the world, he's a top three fighter in the world, so I have got to be on my A game," he explained.
But Joshua believes the fact he won a gruelling contest against Klitschko would stand him in good stead on Saturday.
"Povetkin says he is not the same fighter he was when he lost to Klitschko, he's stronger," said Joshua.
"I can reflect and say I'm the same. When I fought Klitschko, I thought we would have a good boxing match. You know, two tall guys jab, one-two, one-two hook and I'm probably going to knock him out like I did the rest of the fighters. It turned out to be a completely different kind of night.
"Klitschko at the end of his career, he was 39, wanted his hands on the championship belts and he said he was obsessed.
"He was probably in good condition, because most fighters are if they train, but he was obsessed. Povetkin, same thing. Back at Wembley at the end of his career, same age, wants his hands on the belts so I have got to be prepared to go through hell and back.
"Without that Klitschko fight, I wouldn't be as prepared as I am now," Joshua explained.
"I think my well is deep, my heart can definitely go through hell and back."