Floyd Mayweather will try to improve his record to 50-0 against Conor McGregor, who is fighting in his first professional boxing match. (Thomas Johnson,Dani Player/The Washington Post)

LAS VEGAS — In a city built on spectacle, money and games of chance, the fight game’s biggest circus officially rolled into town Friday, one day before the highly anticipated showdown between Conor McGregor and Floyd Mayweather Jr.

The fight fans wore TMT shirts — The Money Team — and TBE hats — The Best Ever — for Mayweather. And they waved Irish flags and sported UFC gear for McGregor.

The oddsmakers agree that Mayweather is an overwhelming favorite. But even though this is the boxer’s own town and the boxer’s own sport, the fans at Friday’s weigh-in — and surely at Saturday’s fight — were overwhelmingly in McGregor’s corner.

“There’s a saying,” McGregor said, “You’ll never beat Irish. … Las Vegas is Ireland now.”

Mayweather didn’t seem fazed. He has reveled in playing the villain role over the years, and the reaction was similar to what the two fighters experienced on their four-city promotional tour.

“The fans can’t fight for you,” Mayweather said Friday. “It comes down to the two competitors.”

Thousands turned out to T-Mobile Arena to watch the two men step on a scale. Though no champions were crowned Friday afternoon, McGregor clearly left the arena feeling emboldened.

He weighed 153 pounds and says he could be as big as 170 when he steps in the ring Saturday. He will be noticeably bigger than Mayweather, who weighed in at 149.5 and likely won’t add much more before the opening bell.

Both fighters looked sufficiently chiseled, but McGregor certainly wasn’t intimidated.

“That’s the worst shape I’ve ever seen him,” McGregor said shortly after the weigh-in. “He looks blown out, out of shape. I’m going to breeze through him.”

The 40-year old Mayweather, who hasn’t fought in nearly two years, smiled watching himself on the big screen overhead and was much more impressed than McGregor with what he saw.

“Weight doesn’t win fights,” he said. “Fighting wins fights. … It won’t go the distance. Mark my words.”

The boxer ignored the crowd’s boos as he spoke. Walking through the arena toward the stage, he twice was pelted with Irish flags. It’s the environment the fighters created for event. Promoting the bout, both were vulgar, loud and juvenile. It turned off many but clearly resonated with some and added to the buzz surrounding the fight.

While there were still tickets available Friday — they was extravagantly priced from $500 to $10,000 — many fans in Vegas planned to save money and watch closed-circuit telecasts.

And so they came out for a show, a fight unlike any other. It’s a hybrid of ESPN and TMZ, sports and reality television, world-famous celebrity and world-class athlete.

After the weigh-in, the two men met face-to-face for the cameras. McGregor barked at Mayweather, his nostrils flaring. The boxer said nothing in return, though Mayweather started chuckling when they broke apart.

Someone will indeed get the last laugh — Mayweather, McGregor or perhaps both, knowing they stand to make a lot of money from people around the world who tune in and open their wallets. Even if fight fans don’t get a good bout, they will hope for an entertaining spectacle.

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