Tyson Fury’s roller coaster comeback could be derailed by Deontay Wilder on Saturday night

It might be a new, improved Tyson Fury, but it didn’t take much from Deontay Wilder on Wednesday to bring the Englishman’s old street-fighting ties to a boil.

Fury, angered by Wilder’s criticism of his milestone upset of long-reigning champion Wladimir Klitschko three years ago, stripped off his designer shirt and raised his fists in a pose of defiance.

Nicknamed “Gypsy King,” in reference to his family’s traveler lifestyle, Fury (27-0, 19 knockouts) invoked his legacy by telling reporters, “I’m going to punch his face in … Wilder is getting knocked out by me.”

A win in Saturday night’s World Boxing Council heavyweight title fight would cap a turbulent three years since his signature victory over Klitschko.

“Icing on the cake,” Fury said. “The first chapter of a new storybook, the beginning of a new life, a new era of Tyson Fury.”

The chapter that immediately followed the Klitschko upset was a pit of darkness and despair, as Fury sank into heavy depression and alcohol and drug abuse. His weight ballooned to nearly 400 pounds and he was forced to give back all three heavyweight belts.

“Listen, when you’ve got mental health problems, no one can say anything to you to make you better,” Fury said. “The more someone goes on to you, the worse you get. So it’s not an easy thing to climb out of. And everyone was talking to me. The more they talk, the bigger the problem becomes. You’ve got to make peace with it and admit you need professional help.”

That’s not easy for such a giant of a man with a bigger-than-life ego. Fury’s younger brother, Shane, said the family became “sick of” the boxer’s derailment.

“He never got any sympathy out of us. We didn’t understand. He was good one minute, bad the next. It dragged you down because Tyson’s the foundation of the family,” Shane Fury said. “He was not a nice person.

“I saw him experiencing it — he was 6-9, [300 pounds] and like a puppy. I had to sleep with him because he was scared, because he thought someone was coming after him, that he was going to get broken … murdered. He literally wouldn’t go to sleep without someone next to him. It was a bad way … and there’s plenty of people in this world who struggle with it.”

Fury said hateful words publicly during his fall about women and gays. He didn’t apologize Wednesday, saying, “I’m just a boxer. I don’t want to talk about the past. I only want to look forward to the future and positivity.”

Wilder wasn’t providing that.

“He wants to entertain the U.S. crowd for giving him so much love for the mental illness and all that … [Fury] caused all that [stuff] himself,” Alabama’s Wilder (40-0, 39 KOs) said. “You took all that [stuff] up your nose, you lifted that bottle … because he wanted to have fun, because he accomplished something big in his life … he sniffed it, he [drank] it.

“If it was me, they’d look down on me. They’d call me a drug addict … so why have mercy upon him for a decision? I ain’t going to have no mercy upon him in that ring.”

Fury has sought to focus on the ongoing inspiration gained by returning to championship fighting form. He won two tuneup bouts while regaining fitness, and has worked with famed trainer Freddie Roach in this camp.

Roach said Fury’s boxing acumen, size advantage and attention to Wilder’s past work are encouraging.

“I’m a very motivated and driven man. When I demand something, I don’t stop — I won’t rest — until the job is done,” Fury said. “I have to put it right.

“It’s been a long, hard road that only made me stronger, more determined. As soon as I said I wanted to box again, I haven’t taken one day off. Not one day of disbelief.”

lance.pugmire@latimes.com

Twitter: @latimespugmire