(CNN) The rise of rugby in America took another step forward this month as Las Vegas welcomed record crowds to its international tournament for the seventh year in a row.

But, aside from the 80,000-plus fans attending across the three days, there was another significant barometer of the game's hopes of cracking the lucrative US sports market.

While 32 men's and women's sides took part in the main sevens events at the Sam Boyd Stadium, some 3,000 players and 260 teams competed at nearby venues in North America's largest rugby competition.

They ranged from under-14 level to seniors, and included one highly-rated college football star who has turned down offers from NFL teams to focus on rugby.

"We need to invest today to be able to get the rewards 10, 15 years from now," he told CNN's World Rugby show in Vegas.

"In the US it's still a start-up sport relative to some of the more mature sports. That gives us a lot of opportunity because our numbers are growing, whereas a lot of the other sports that would considered mature sports in the United States are actually having membership decrease, so that's exciting."

Teaching the kids

Fiji sevens legend Waisale Serevi coaches children in the US and around the world.

USA Rugby is targeting the five-to-13-year-old grassroots players, and it has enlisted the help of one of the greatest exponents of the sevens game.

Waisale Serevi is a rugby god not only in his native Fiji, but across the international game after a trophy-laden career.

Having relocated to Seattle since his retirement, his coaching company Atavus has been working in schools around the country teaching kids basic rugby skills.

Photos: America's growing love for rugby Photos: America's growing love for rugby The ever-increasing popularity of the Las Vegas Sevens is helping rugby to become one of the fastest-growing sports in the United States. Hide Caption 1 of 15 Photos: America's growing love for rugby The Las Vegas Sevens is always a fan favorite, but the two recent editions have been particularly special with USA winning back-to-back title Hide Caption 2 of 15 Photos: America's growing love for rugby The 2017 event attracted record crowds to Sam Boyd Stadium for the seventh consecutive year with an attendance of 80,691 across the three days. Hide Caption 3 of 15 Photos: America's growing love for rugby Like many sevens events around the world, Vegas inspires a party atmosphere with spectators coming in fancy dress. Hide Caption 4 of 15 Photos: America's growing love for rugby The 2017 attendance was a slim increase on the previous year, which brought in 80,138, including these fans dressed as Elvis Presley. Hide Caption 5 of 15 Photos: America's growing love for rugby The USA has enjoyed its best start to a sevens season this year, finishing runner-up at the first four tournaments. Hide Caption 6 of 15 Photos: America's growing love for rugby Over 100,000 fans attended the Rugby World Cup Sevens in San Francisco, the best-attended rugby event ever in the USA. Hide Caption 7 of 15 Photos: America's growing love for rugby In common with rugby's US sports rivals, cheerleaders play a big part in the entertainment schedule at Vegas -- which over the years has included Cirque Du Soleil and fighter jets. Here members of the USA Sevens Sweethearts perform during the 2015 tournament. Hide Caption 8 of 15 Photos: America's growing love for rugby The 2016 tournament was broadcast on NBC and its Sports Network. It reportedly reached national and international audiences in over 400 million homes and 147 countries. Here a Samoan rugby fan supports his team in 2016. Hide Caption 9 of 15 Photos: America's growing love for rugby A security guard chases a costumed fan after she ran on the pitch during the 2015 Cup Final match between Fiji and New Zealand. Hide Caption 10 of 15 Photos: America's growing love for rugby It required two guards to finally bring the woman to the ground. Hide Caption 11 of 15 Photos: America's growing love for rugby Security was busy that day, as this fan also invaded the pitch before Fiji beat New Zealand. It was the All Blacks' fourth successive defeat in Vegas finals. Hide Caption 12 of 15 Photos: America's growing love for rugby This fan also took center stage during a 2014 match between the US and Spain. Hide Caption 13 of 15 Photos: America's growing love for rugby Players get close to the crowds in Vegas. Here members of the Canadian team pose with fans following a 2014 match against Samoa. Hide Caption 14 of 15 Photos: America's growing love for rugby US speedster Carlin Isles, who bagged a try in the 2018 final, is popular with the home supporters. Here he wears a cheese hat at the request of a fan taking his photo after a 2014 game. Hide Caption 15 of 15

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"When I was young, I didn't have the opportunity for top rugby players to come and help me go to the next level," the 48-year-old tells CNN.

"So I thought after I retired, without rugby there's no Waisale Serevi -- I would love to give back ... to get young kids, to introduce them to rugby and then try to teach from all different kinds of levels."

As it stands, many American converts come to rugby in their later teenage years, or even their 20s.

Serevi and Payne hope kids will learn rugby skills long before they get to college, so they are not catching up when they reach higher levels in the game.

"Not all people can play football, not all people can play soccer, but rugby is a great opportunity for any shapes and sizes," Serevi says. "Whether you are a big guy or a small guy like me, you still have an opportunity to play rugby.

"Kids came to me and they said, 'I came from football, I came from soccer, this and this, but rugby, it's the best sport because I can score tries, I can tackle someone and I can run around people' -- that's why they are so excited."

'They want to be Tom Brady'

Nate Ebner (R) congratulates Tom Brady after the New England Patriots' 2015 Super Bowl win.

USA Sevens men's coach Mike Friday says American rugby needs a major international star as a role model to attract young talent that might otherwise end up playing and following football.

"It hasn't got the legacy that they have in New Zealand or England, so they haven't got the history whereby every young player wants to be an All Black or play for England. They want to be Tom Brady," the Englishman told CNN in Vegas.

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Rugby was Nate Ebner's first sporting love, but he returned to the New England Patriots after the Games and was rewarded with his second championship ring in February.

"I'd do it again in a heartbeat, no regrets," he told CNN in Vegas, reflecting on the opportunity to take a break from his NFL career and represent his country.

He said the 12 months from rejoining the US rugby setup to helping the Patriots' extraordinary comeback win against Atlanta Falcons was "the best year of my life."

"Rugby has the hearts of Americans, no doubt," Ebner adds. "The excitement and the feedback that I got from (people) watching in Rio, that have never watched rugby, that watched simply because they heard my story with the Patriots and they were watching the Olympics ... it has been amazing.

"Everyone that plays rugby in the United States loves it, diehard, they bleed rugby if they play it. The people that are watching think it's an extremely exciting game, especially the seven-a-side -- they don't have the understanding of 15s yet, so sevens has been a great tool for the United States to really get the game out there."

With sevens returning to the Olympics at Tokyo 2020, Ebner will have another big career decision to make.

"Just watching it here I want to put my shorts on and go play with the club teams or whatever, but at some point it'll happen -- it's just a matter of when and how," the 28-year-old says.

"The NFL holds a big say in that, for right now, but we'll see -- one day."

The 'brotherhood' of rugby

Psalm Wooching has decided to play rugby rather than pursue an NFL career.

One player who turned down the attention of NFL talent scouts is Psalm Wooching, former starting linebacker at the University of Washington.

The 23-year-old said he had 20 agents calling him after helping the Huskies reach the 2016 college playoffs.

However, he has decided to focus on rugby -- which he first experienced on a childhood Christian mission to New Zealand, and played until high school in his native Hawaii.

"It was a hard decision for me -- I went ghost, I went silent for like a month and half after the season just to, you know, debrief, look back on my career," Wooching told CNN at the Vegas invitational event.

"At the end of the day, it came down to the love and the passion of this game. I think the thing that attracts most people to NFL is the income, the money and all that, and what attracts me the most is the brotherhood and the stuff like that you build through rugby."

The major leagues

Ebner in action for the US against Brazil at the Rio 2016 Olympics.

While soccer has grown in the States since the introduction of the MLS in 1993, rugby is still waiting for its own national league.

Ebner believes this will be a vital growth point for the game -- and essential if the sport ever hopes to rival the NFL.

Last year the five-team Pro League was launched, but its second season has yet to be confirmed. In December, owner Doug Schoninger wrote a letter informing players their contracts had been terminated, and cited disagreements over terms with USA Rugby.

The ruling body released a statement denying the allegations.

"We're trying to figure out what's going to work, trying to get a league established," Ebner says.

"We're at that very infant stage of that with rugby, and I think leagues need to be established, more broadcasting and events like this that bring the people in to see it and get that growth and foundation, to get players coming in, starting at a young age and start to play professionally.

"That's where it's going to start, and then maybe we can have the conversation until how long before it competes with NFL."

Building on the Rio surge

Dan Payne (R) tackles South Africa's Schalk Burger during a match at the 2007 Rugby World Cup.

Payne took charge of American rugby's top job just before the Olympics.

A former All-American wrestler, he was also a latecomer to the game, but went on to represent the US at the 2007 Rugby World Cup and was an assistant coach for the national team.

"Having rugby in the Olympics gives a legitimacy and an overall awareness that we haven't been able to get previously," he says.

Payne says the US Rugby website's traffic spiked from its usual 200-300,000 daily visitors to 35 million during the six August days of the men's and women's Olympic program.

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"Naivety somewhat throughout our country is an asset," he claims. "If we were to win a medal in the Olympics, say if we just won a bronze medal, the majority of America is going to think we're the third best in the world at rugby, you know, because they wouldn't really know the difference between 15s or sevens."

As it happened, Friday's team missed out on a quarterfinal place by the narrowest of margins, while the US women made the last eight but lost to eventual runner-up New Zealand.

As well as the 2018 edition of the Vegas tournament, the US will have another showcase opportunity next year when San Francisco hosts the Rugby World Cup Sevens for both genders.

"Every time we have a large event it allows us to increase the standard within that major market, and then we incrementally build on that year over year, so it's going to be a phenomenal experience," Payne says.

"I think we're right on the cusp of really being able to commercialize and monetize the sport. The participation numbers are continuing to grow, the awareness is growing."