By Edward Chaykovsky

IBF heavyweight champion Anthony Joshua (18-0, 18 KOs) is very mentally focused on the biggest fight of his professional career.

On April 29, before an anticipated crowd of 90,000 fans, Joshua will collide with former division ruler Wladimir Klitschko at Wembley Stadium. The vacant WBA, IBO titles will also be on the line.

Klitschko is also looking to reclaim lost glory, as he's fighting for the first time since the shocking twelve round decision loss to Tyson Fury in November 2015.

Joshua has been highly criticized by some observers for his level of opposition. On paper, Klitschko presents by far the biggest challenge of his career and the most experienced opponent out there.

"I tried to play it down, I'm quite like that - 'It's only another fight'," Joshua told Sky Sports News HQ. "But emotionally you will always change how you feel about something. I'm going into the stage, emotionally, where this is my defining fight.

"I've done what I had to do to become champion, which is great. But when we talk about defining fights, this is one that could change the perspective of my credibility within my industry. That's why this fight is important.

"That's why I want to do certain things before I get into training camp, because that will be my sole focus no matter the opportunities on the table outside of my training camp. This is my goal, this is it. This is the heavyweight championship."

Joshua's promoter, Eddie Hearn, is looking to make Joshua into an international superstar. Should Joshua overcome the challenge of Klitschko, then Hearn's goal is finalize a unification with WBC world champion Deontay Wilder (37-0, 36 KOs).

"Anything can happen, but I love the Deontay Wilder fight. The Americans are starting to go mad for Anthony Joshua. Wilder against Joshua can be built into a huge fight. Two undefeated, fast, big-punching heavyweights. But I think at the moment, the pure focus, because of the toughness of the fight, has to be Wladimir Klitschko," Hearn told Sky Sports. "You come through and it's no turning back, it's big fights only."