Eddie Hearn, who promotes Anthony Joshua, believes the boxer will rule the world of boxing if he beats Klitschko.
Joshua will have the chance to add the WBA ‘super’ title to his IBF belt when he faces Klitschko at Wembley on Saturday.
90,000 fans will be in attendance at Wembley to watch the historic fight, which will be televised worldwide.
“He becomes the biggest star in British sport and the biggest star in world boxing,” Hearn told Sky Sports. “It’s early in his career, it’s his 19th fight, so masses of pressure.”
Asked about Joshua’s meteoric rise, Hearn said: “We talk about this 10-year plan, we’re kind of having a legacy fight within the first couple of years. It’s here, the timing is perfect.
“He could sell out any arena, against anyone, but he wants to be remembered for the big fights.
“This opportunity won’t be there forever. You fight Klitschko now, or it never happens. He wants to be in those big fights, he wants to take on the very best.”