LAS VEGAS — For three years, Gennady Golovkin dreamed of fighting Canelo Alvarez. Golovkin, boxing’s longest reigning champion, saw in Alvarez a kindred spirit, the opponent who could help him make the spectacular fight he so wanted to give.

As a 5-year-old in the former Soviet Union, Golovkin watched, transfixed, as ex-welterweight champion Sugar Ray Leonard moved up to middleweight and somehow lifted the title from the fearsome and seemingly invincible Marvin Hagler.

“I’m a huge, big boxing fan and Hagler and Leonard, I watched it on television when I was small and I said, ‘Wow! I want to do that,’ ” Golovkin explained.

He’d sparred with Alvarez in 2011 at the Wild Card Gym in Hollywood, California, and was intrigued by the red-headed Mexican’s talent and potential. In 2014, Golovkin knew that Alvarez could be Leonard to his Hagler, Sugar Ray Robinson to his Jake La Motta.

After years of start-and-stop negotiations, Golovkin promoter Tom Loeffler of K2 finally wrapped up a deal for Saturday’s bout between the two rivals for the middleweight title on one condition: Alvarez had to defeat Julio Cesar Chavez Jr. on May 6 in Las Vegas.

On May 5, Loeffler phoned Golovkin and urged him to get ready to hop on a plane to attend the Alvarez-Chavez fight. Loeffler knew that if Alvarez won, as expected, there would be a post-fight news conference to announce that, finally, Golovkin-Alvarez had been signed.

Golovkin, though, refused to go when Loeffler called.

It wasn’t that he’d suddenly had cold feet. A year earlier, in May 2016, Golovkin had been ringside in Las Vegas when Alvarez had fought Amir Khan. After Alvarez blew out Khan with a devastating knockout, he ran over to where Golovkin was seated at ringside and in the ultimate display of machismo, invited Golovkin into the ring.

At the post-fight news conference that night, promoter Oscar De La Hoya rambled on and on about how he planned to contact Loeffler the next day and begin negotiations to make the fight.

It did not happen, though, and Golovkin was left at the altar, disappointed, as Alvarez fought far less competitive fights against Liam Smith and then Chavez.

Golovkin refused to make that trip on May 5 because he’d seen it all before.

“He didn’t want to be used as a prop again,” Loeffler said.

But by the next morning, Loeffler had convinced Golovkin that the deal was done, contingent upon Alvarez defeating Chavez.

Golovkin, Loeffler and trainer Abel Sanchez hopped a plane to Las Vegas for the fight and for their date with history.

Their bout for middleweight supremacy is only days away now, and Golovkin’s countenance reflects that. The match he’s been chasing for three years has finally arrived. He’s not celebrating the birth of his first daughter and second child, which occurred last Friday. He won’t even speak his daughter’s name, for fear of breaking his concentration on the task at hand.

“No talk about family,” the normally affable Golovkin said. “This is boxing. This is no game.”

Golovkin had been frustrated so frequently before. When he was fighting out of Germany, he was desperate to fight then-champion Felix Sturm. That fight never happened.

He arrived in the U.S. with only one bag, which contained his boxing gear and some clothes. He wasn’t coming for vacation. He was coming to work.

Upon his 2010 arrival in the U.S., he had his eye on Sergio Martinez, then regarded as the finest middleweight in the world. He never got close to a fight with Martinez. At various times, there was chatter about fights with Alvarez and Chavez. The answer was always the same: Thanks, but no thanks.

Now, finally, Golovkin has the opportunity he’s sought for so long. He doesn’t care that it’s in Las Vegas, the Fight Capital of the World, where so many of the sport’s most memorable fights have been held.

Asked if he were excited to be making his Las Vegas debut, he sniffed and said, “It’s not special. I want to fight. … I just want to get into the ring. It doesn’t matter where.”

Golovkin is not much of a talker even in the best of times, and he’s turned Sanchez, his highly regarded trainer, into an unofficial spokesman and trash talker.

It’s been Sanchez who has been talking and talking and talking, keeping Golovkin’s name in the news and getting headlines for his outrageous comments.

Sanchez carries a gym bag in the back of his late-model SUV stuffed with T-shirts and caps that have his fighters’ names on them.

He brought one of the shirts to a media session with Golovkin at the MGM Grand on Tuesday. This one didn’t have Golovkin’s name anywhere on it, though.

At a break in the conversation, Sanchez said, “I just know that the sky is blue, water is wet and on Saturday, Cinnamon is toast.”

He then held up a black T-shirt with white block letters that read, “Cinnamon is toast.” Canelo, Alvarez’s nickname, is Spanish for cinnamon.

Golovkin has gone out of his way to point out that he’s not invincible and to insist that he respects Alvarez.

“Everyone has a chance against me,” Golovkin said. “That’s the nature of boxing. One punch can change everything.”

Thirty-three times in 37 professional fights, one punch was enough. Golovkin finishes his opponents in ruthless fashion. He’s 37-0 with 33 knockouts and has a reported amateur record of 345-8. He has never been knocked down.

He spoke with a gleam in his eye of how “Canelo has destroyed everybody; he has looked very good,” knowing that a win over such a highly respected fighter will finally allow him to take his place in the pantheon of the sport’s all-time greats.

“This is a true fight, not a show, not a money fight,” Golovkin said, jabbing at the Aug. 26 bout between Floyd Mayweather and UFC lightweight champion Conor McGregor. “Well, there is a lot of money in this, of course, but this is a historic fight, who is the pound-for-pound best, who is the biggest face of boxing.”

He’s been great for years, but Golovkin has finally hit the big time. And by his actions and (extremely) few words, he’s showing he plans to stick around a while.

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