Conor McGregor during open workouts on Oct. 3 at the MGM Park Theater in Las Vegas ahead of UFC 229. (Getty Images)

LAS VEGAS – As Conor McGregor left his dressing room at TD Garden in Boston on Aug. 17, 2013, to make his way to the cage for his second fight in the UFC, the house lights went dark.

The crowd erupted, and UFC color analyst Joe Rogan marveled at what he was seeing.

“Wow,” Rogan said upon hearing the crowd’s guttural roar for McGregor. “I really can’t remember the last time a guy with one UFC fight – well, Brock Lesnar, but first of all, he’s a 300-pound giant of a man who looks like a freak. You look at him and you go, ‘What is that? Is that even human?’ But this guy’s a normal dude from Ireland with one UFC fight and this place is on its feet.

“I know this is Boston. I know they’re Irish. I grew up here. They go crazy for anything Irish. But this is something unusual. This kid has got something.”

If Rogan only knew how prophetic those words would prove to be.

When McGregor makes the walk to the Octagon at T-Mobile Arena on Saturday to challenge Khabib Nurmagomedov for the lightweight title in the main event of UFC 229, he’ll do so as one of the highest-grossing fighters who ever lived. The UFC doesn’t release its pay-per-view numbers publicly, but McGregor appears to have sold more than anyone who has fought on pay-per-view other than boxers Floyd Mayweather, Oscar De La Hoya, Mike Tyson, Evander Holyfield, Manny Pacquiao and Canelo Alvarez.

It’s a staggering number for a guy who didn’t join the UFC until 2013.

He was on government assistance at the time, but on Saturday, he’ll make a purse that could creep toward $50 million. He’ll earn millions more in endorsements.

He had a vision of how it would play out, even when no one knew his name. In 2013, he said several times, “I’m not here to take part. I’m here to take over.”

Now, he’s a global star, and by any measure he’s turned his vision into a reality. In the cage, he’s one of the best pound-for-pound fighters in the world, ranked No. 2 in the current UFC ratings behind only heavyweight and light heavyweight champion Daniel Cormier.

McGregor, who is 21-3 overall in MMA, is one of only two men, along with Cormier, to hold two weight class championships simultaneously and one of only five to hold titles in two divisions at any point. In addition to Cormier and McGregor, Randy Couture (heavyweight and light heavyweight), B.J. Penn (welterweight and lightweight) and Georges St-Pierre (welterweight and middleweight) are the others to do so.

He’s already among the top individual pay-per-view sellers of all time, and he’s poised to become just the second man, joining Mayweather, to have participated in more than one fight that sold two million on pay-per-view.

The only bouts that have done that are Mayweather-Pacquiao in 2015, at 4.6 million; Mayweather-McGregor in 2017 at 4.4 million; Mayweather-De La Hoya in 2007 at 2.48 million and Mayweather-Canelo Alvarez at 2.2 million in 2013.

It seems a lock that Nurmagomedov-McGregor will break the UFC pay-per-view mark of 1.65 million set in 2016 by McGregor and Nate Diaz at UFC 202. It’s a good bet to surpass two million and is trending, UFC president Dana White said, to reach three million.

View photos Eddie Alvarez fights against Conor McGregor in their lightweight championship bout during the UFC 205 event at Madison Square Garden on Nov. 12, 2016, in New York. (Getty Images) More

McGregor hasn’t fought an MMA fight since Nov. 12, 2016, when he defeated Eddie Alvarez to win the lightweight belt in a fight that set the UFC record for largest gate in history at $17.7 million. The gate on Saturday at T-Mobile is expected to be just over $17 million.

McGregor, who had a child, is expecting another and boxed 10 rounds with Mayweather since his last UFC appearance, has picked up where he left off.

Asked for a prediction, McGregor didn’t miss a beat.

“Domination, his head bouncing off the canvas,” McGregor said. “… He’s a glass jaw. The Chechens, my Chechen friends, the soldiers, they told me they have chicken jaws in Dagestan. And I believe them, because I know a glass jaw when I see one.

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