Promoter Eddie Hearn says he is "nervous" about Anthony Joshua's showdown with Alexander Povetkin at Wembley on Saturday.
Joshua, the WBA, WBO and IBF world heavyweight champion, faces 39-year-old Russian Povetkin, who has only been beaten once in his 35-fight career - by Wladimir Klitschko in 2013.
"It's a massive show, a massive event with the biggest star in world boxing and the best heavyweight in the world," Hearn said.
"But I'm a bit nervous because I think this is a much tougher fight than people give it credit for. Boxing fans know how big a fight this is and how tough a fight this is.
"Outside of Klitschko I think on paper this is the toughest fight of Joshua's career so far.
"He's expected to win. But Povetkin punches very hard, he's got a good chin, he's durable. I expect this to be a real test."
PA
