Anthony Joshua, a heavyweight who will take on Jermaine Franklin on April 1 at London's O2 Arena, claimed he has returned to boxing with all of his heart.
The 33-year-old Briton seeks his first victory since 2020.
Joshua said he was more serious than ever before about his boxing career.
"I've always tried to make an empire but I made a conscious decision last year to put my heart into boxing and nothing else. Throughout my career, this is probably the most serious time I've taken it," Joshua said.
Joshua travelled from Texas to London with Derrick James, his new coach, to attend the press announcement.
"I'm a serious person I'm not there for anything else. I'm there to put my head down and get ready for a fight. With Derrick here, he's got some tricks up his sleeve for sure and we're looking forward to April," he said.
Meanwhile, James believes the world hasn't seen the best of his new fighter.
"The world hasn't seen the best of Anthony Joshua," James said. "He's a great fighter. Great athleticism, great foot movement, very intellectual first and foremost. He understands this sport and understands what I'm asking him to do."
For the first time in eight years, the two-time heavyweight world champion competes in the O2 Arena without defending a world championship. This is his first fight there since 2016.
Joshua has fought seven times since his last contest at the O2, and most of those contests have taken place at huge outdoor arenas.
The 29-year-old American Franklin, who lost to Dillian Whyte last December on points, is clearly the underdog.
But Oleksandr Usyk's two demoralising losses have put Joshua at a career crossroads.
As he attempted to reclaim the united heavyweight championships from Usyk in August, Joshua was defeated by a split decision.
The Watford fighter has lost three times in his career in 27 fights, including a shocking defeat to Andy Ruiz Jr. in 2019 that he eventually avenged.
On the other hand, Franklin, who lost a close majority decision to Dillian Whyte last November, believes he is ready to go to war.
"I feel like I won the fight. This is boxing. I'm not going to cry about it. I've got the utmost confidence, I believe I could beat anybody. There's never a doubt in my mind. If you've got doubt, you're in the wrong sport.
"It'll be an excellent moment in my career. I've got the will, I've got the heart for it. I'm ready to go to war."