Who is Rocky Fielding and how did he land a fight with Canelo Alvarez?

Nearly all the boxes you’d want checked for an underdog apply to Canelo Alvarez’s Saturday night opponent at Madison Square Garden.

Michael Fielding goes by the nickname “Rocky”, a nickname he picked up when a friend said the then-10-pound baby looked like a rock.

He qualified for this high-profile U.S. debut by capturing the World Boxing Assn.’s secondary super-middleweight belt in surprising fashion by technical knockout over Tyron Zeuge in Germany this July.

Since his win, Fielding has trained for the Alvarez fight by running through the streets of his hometown in Liverpool, England, cheered on by neighbors who’ve known him since he was a child.

Saturday night, Fielding (27-1, 15 knockouts) hopes to keep the surprises coming against middleweight champion Alvarez (50-1-2, 34 KOs) who is seeking to become the ninth Mexican fighter to win a world title in a third weight class.

“Everything about it is a big challenge and I look forward to it all,” Fielding said. “I’m fighting one of the best pound-for-pound boxers here at Madison Square Garden.

“No one gave me a chance to win in Germany except my family, but I went there and won a world title. I proved myself. That’s all I need to do now. That’s all I need to bring to this fight. When they don’t give me a chance, I look forward to it.”

The Westgate Race and Sports Book in Las Vegas lists Fielding, 31, as a 9-to-1 underdog, and Alvarez is favored to end the fight by knockout before the middle of the seventh round.

“I’m not selling this fight as the toughest fight for Canelo, but I’m not selling this as the easiest fight for Canelo either. It’s a challenge,” Alvarez promoter Oscar De La Hoya said.

“The fact that Canelo’s moving up to 168 pounds, and when you look at this guy, Rocky, he’s a huge guy.”

Fielding, at 6-foot-1, has five inches on Alvarez, and the Brit’s 75-inch reach is 4 ½ longer than Alvarez’s.

“I’ve got to use everything I’ve got to the best I can,” Fielding said.

De La Hoya, after watching the taller Julio Cesar Chavez Jr. blow his chance to exert a size advantage in his 2017 fight against Alvarez, thinks Fielding will need to use his height and reach to pull off the upset.

“If I was Rocky, why would I fight him on the inside? Canelo has to be the aggressor,’ De La Hoya said. “Canelo has to cut off the ring and press the action.”

Despite Alvarez being a clear favorite, there are still some lingering doubts about the Mexican champion’s return to the ring.

Is Alvarez fighting too soon after the defining bout of his career, the Sept. 15 majority decision victory over Gennady Golovkin? The fighter and De La Hoya say no, vowing that increased activity is good for a fighter.

Has he paid too much attention to his new 11-fight, $365-million deal with the streaming service DAZN?

“This is dangerous for Canelo when you consider it’s the chance of Rocky’s lifetime. He has everything to gain,” Golden Boy President Eric Gomez said, “and nothing to lose.”

Being raised in tough Liverpool, Fielding has developed friendships with gritty fighters such as recently retired cruiserweight Tony Bellew and UFC fighter Darren Till.

“We don’t back down from anybody. We’ll fight anyone, and give it our all,” Fielding said.