Eddie Alvarez has faced bigger odds than beating UFC’s Conor McGregor

UFC lightweight champion Eddie Alvarez calls himself “the complete opposite” of the man he’ll fight Saturday night at Madison Square Garden, the popular Conor McGregor.

“For him, it’s a big show: what you can see,” Alvarez said. “The fights for me are always about what you cannot see, the intangibles. It’s about what’s inside — what really is inside.”

While McGregor has been on the fast track to stardom by complementing his feats in the octagon with colorful verbal boasts and assaults, Philadelphia’s Alvarez, 32, is nicknamed the “Underground King” for toiling for at least nine professional MMA organizations.

“It happened slowly for me; it didn’t happen overnight,” said Alvarez (28-4 with 15 knockouts). “But I had an idea and belief in my mind that if I wasn’t concerned with what I was getting, and only concerned with what I was giving, I would never grow bitter or angry.”

Alvarez endured a yearlong contract squabble with the mixed martial arts organization Bellator, which claimed it had the right to match the UFC offer Alvarez wanted.

He lost his UFC debut but rallied with three consecutive victories, including his first-round knockout of Rafael dos Anjos to capture the lightweight belt.

After avenging a loss to Nate Diaz in August, McGregor pushed for Alvarez next, and he gets him in a UFC 205 main event that marks the UFC’s first fight card in New York.

Following his public workout Wednesday on the Garden’s basketball floor, Ireland’s McGregor, seeking to become the first fighter in UFC history to wear two belts simultaneously, predicted Saturday’s UFC 205 main event will be a first-round knockout.

Alvarez doesn’t intend to go down that easily — or at all.

Raised in the rugged town of Kensington, Pa., outside Philadelphia, Alvarez said he comes from “where the odds are against you, a place that’s most known for how good the heroin is … so I’ve always been fighting since I’ve grown up.”

MMA reporter Ariel Helwani, who accompanied Alvarez on a tour of his former hometown recently, said there were “syringes and people passed out on the ground. … It’s the worst place I’ve ever been to, and Eddie wouldn’t do the interview unless we had two fully suited police officers at our side.”

Alvarez found a way to avoid the darkest corners of the hard streets.

“You begin to think that’s what life is. So I made sure I was always in a gym or in a sport,” he said. “I boxed. I did track and field; I did basketball, football, any sport I was able to sign up for.”

He was sent to a Catholic school and was introduced to mentors outside his hometown, including a wrestling coach.

“That sort of changed me. It sparked that competitive drive in me, and that’s probably one of the main reasons I’m here today,” Alvarez said.

“I never really lost a fight [around Kensington], so when I first started [pro MMA] fighting … the crowds kept getting larger and larger. I won my first 10 fights by knockout. The money was getting larger at the same time.”

Alvarez was a mason in 2005, earning $45,000 a year before taxes, when another fight promoter approached him, offering double.

“So I decided to make an investment in myself and go all in,” Alvarez said.

By the time he reached the dos Anjos title shot, Alvarez said, “It wasn’t about how dangerous the opponent is. But it was me knowing how much work I’d put in and how deserving I am of success and that title. No one was going to keep me from that opportunity. Sometimes you only get it once.”

As McGregor arrives, Alvarez is reminded of his mantra to avoid obsessing over others’ good fortune, as McGregor has fought and talked his way toward the largest guaranteed purse in history.

“The right thing to do is just ask what you can give, and then let things manifest in the time they’re supposed to. So what he gets is what he gets. Come Saturday, I’m going to take everything from him, regardless of what he’s done in the past.”

“We live in an amazing country, and he’s taken advantage that there’s freedom of speech no matter how ridiculous some things sound. You don’t need the burden of proof. He’s using that, but a lot of his talk is self-talk — him trying to convince himself of what he’s saying. I think it’s therapeutic.”

Alvarez said he envisions a victory thanks to his intensive wrestling training and power punching.

In other words, actions. Not words.

UFC 205

When: Saturday, 7 p.m. Pacific

Where: Madison Square Garden

Television: Pay-per-view, $64.95; Preliminaries on Fox Sports 1, 5 p.m. Pacific

Fight card: Conor McGregor (20-3) vs. Eddie Alvarez (28-4) for Alvarez’s lightweight belt; Tyron Woodley (16-3) vs. Stephen Thompson (13-1) for Woodley’s welterweight belt; Joanna Jedrzejczyk (12-0) vs. Karolina Kowalkiewicz (10-0) for Jedrzejczyk’s women’s strawweight belt.

lance.pugmire@latimes.com

Twitter: @latimespugmire