Anthony Joshua admits a world title defeat against new challenger Carlos Takam could tarnish his legacy "for a lifetime".
The unbeaten 28-year-old will defend his WBA 'super' and IBF heavyweight titles against Takam, who replaced the injured Kubrat Pulev as the next opponent for Joshua in Cardiff on October 28, live on Sky Sports Box Office.
Joshua is proud of his perfect professional record, with all 19 of his victories coming by knockout, and fears that Takam would damage his reputation permanently with a shock win at the Principality Stadium.
He told Sky Sports News: "In boxing, I think it's a sport that's unforgiving in the sense that, if Takam beat me that loss will stay on my record for a lifetime, that will always be in my legacy.
"It's not 'oh, he was a world champion and he done well for the sport of boxing. No, no, no he was 19-1 - that's Anthony's legacy and I just don't want that blemish on my record right now."
The France-based Cameroonian has demonstrated his durability throughout his career, only suffering one stoppage defeat in 39 fights with 27 knockout wins to his name.
Joshua revealed he is feeling extra pressure after being forced to prepare for Takam at short notice and believes he could be facing another brutal battle, a few months on from his 11th-round knockout of Wladimir Klitschko at Wembley.
People have said 'Joshua what round?' I think we're going for a 10 to 12 round here you know. This guy's head is like a block of cement.
"Takam is already as tough as they come," said Joshua. "He's so tough. He just keeps on walking forward and that's disheartening for a fighter.
"When I'm in there with him, it will be interesting to see how game and ready he is, and what fire he is ready to go through.
"I've had some sparring partners that have been coming and trying to knock me out and I've had to dig in a bit and give them a few body shots back and so on.
"My inside game has definitely improved, so I think if we have to stand on the inside and start trading off, it will definitely be an entertaining fight for the people watching.
AJ's tougher test in Takam
Anthony Joshua must refocus his troubled mind on new opponent Carlos Takam
"People have said 'Joshua what round?' I think we're going for a 10 to 12 round here you know. This guy's head is like a block of cement."