NRL's brutality on show in USA as Roosters stun Broncos

But an incident in the second half threatens to overshadow the spectacle, with claims from the Broncos that Roosters recruit Spencer Leniu levelled a racial remark at Indigenous five-eighth Ezra Mam during a scuffle.

The match review committee is set to probe the incident in the coming days after referee Adam Gee placed it on report at Allegiant Stadium.

If Saturday evening's first game (Sunday AEDT) educated the USA on razzle-dazzle rugby league, the second was all about the uncompromising physicality of the 13-man game.

Victor Radley and Lindsay Collins were chief enforcers as the Roosters ground the Broncos into the turf, helping their side claim a major scalp in their first start this season.

"I thought the physical contact and the continuity of the footy that us and Brisbane played was quite high for round one, or any stage," said Roosters coach Trent Robinson.

Under the bright lights of Sin City, the Broncos were unable to atone for their own sins from the 2023 grand final, bullied onto the back foot after conceding early.

"Before I left home, they said 'It's always hard to win in Vegas'. They weren't wrong; it was a tough game," said Broncos coach Kevin Walters.

"Our attack just never flowed. We just didn't execute what we came here to do, really.

"We've got plenty to work on, but it is round one."

Reece Walsh gave the Broncos hope either side of the break.

First, he slipped past Joseph-Aukuso Suaalii and kicked through the line for a flying Deine Mariner, who made it 8-4 at halftime.

Then Walsh had a try of his own in the early minutes of the second half, after the ball travelled through hands on the left side.

But the Broncos, for all their firepower up forward, could not match the Roosters' aggression and appeared to be missing Dolphins recruit Tom Flegler as they fought to stay in the game.

As the sides showed America all that rugby league had to offer, Roosters centre Joey Manu reminded Australia just how much he'll be missed when he moves to rugby union in 2025.

Manu's move overseas has not yet been confirmed, but Robinson held little hope of retaining the 27-year-old.

"Joey's not making (the decision) on a whim. He's thought about it," Robinson said.

"So I just step back and make sure he's open with me about what he's thinking. If that changes, I'll be doing cartwheels."

"We want to leave that door open but there's no pressure for us."

Manu picked off a Mam pass in the opening five minutes, cruising 30 metres to score and help his side take early advantage.

But the New Zealand international saved his best trick for after the break, firing a no-look flick pass around the corner to send Junior Pauga over for a spectacular try down the right.

It was reminiscent of Joey Leilua's famous flick pass to Jordan Rapana at Leichhardt Oval in 2016, but the only thing to which the American audience could've compared it would've been a magic trick from a Las Vegas show.

Walsh fought hard, and Adam Reynolds looked more comfortable playing within the confines of the smaller field as the game went on.

But James Tedesco, outstanding after a patchy 2023, sent Radley over to seal the result in the final 10 minutes and reward the lock forward for his leadership in the forward pack.

Australian Associated Press