Blaine Scully is in determined mood as he strides into the Mary Rose Suite of the USA's Portsmouth base. "If you're a competitive guy, participating isn't good enough," he says when quizzed about American intentions over the next six weeks. "And it's not for this team. I think that's a really important mindset to have."

Scully was unattached when he travelled with his country to New Zealand for the 2011 Rugby World Cup, sharing the No.15 shirt with Chris Wyles. Now he starts the 2015 tournament on the back of two highly productive seasons in the Aviva Premiership with Leicester Tigers that have earned him a move to the Cardiff Blues. He refuses to give much thought to his new life in Wales yet, though, as he plots the Eagles' path to the quarterfinals.

Just like Scully, the USA have undergone something of a transformation since the last edition of rugby's global showpiece. Gone are days of turning up and being happy to be there; Mike Tolkin's side are determined to leave their mark. And, moreover, the squad feels it has a duty to do just that.

"[Rugby] is the fastest growing team sport in the States at a youth level which is awesome. We're attracting some of the top teams in the world to come and play, which allows us to showcase the game in a very real way," Scully says. "Overall, it's pretty exciting times for us and this is kind of how we see ourselves in the context of this World Cup too. We're a part of this movement really in the States, and it's our job and our responsibility to do the absolute most that we can to put in a performance worthy of all that."

The game has gone from strength to strength in the USA since 2011, even if the Eagles' performance in New Zealand was fairly unremarkable. A team coached by Eddie O'Sullivan lost comprehensively to Australia, Ireland and Italy while beating the lowest-ranked side in Pool C, Russia. Yet that 13-6 victory -- one of only three the USA have managed in six World Cup finals appearances -- seems to have helped rouse a nation's interest. "In 2011, during and after the World Cup, there was such a buzz about it and we went 1-3," Eagles coach Tolkin says. "We beat Russia but there was still a buzz around the World Cup."

Fast forward four years and, as Scully notes, rugby is now the fastest-growing team sport among America's youth - thanks in no small part to USA Rugby's award-winning Rookie Rugby program - and that interest has filtered through to the senior game.

Eight months after the squad flew home from New Zealand, they played Italy in front of 17,000 people in Houston, Texas. That represented a record for a national team game, and mark raised to 20,181 the following year before 61,500 crammed into Soldier Field for the visit of New Zealand last November. Two weeks ago Australia were the visitors to Chicago, where 23,112 fans witnessed a match in which the Eagles trailed by just four points at half-time and remained pretty close until the final quarter. Americans are becoming increasingly accustomed to watching tier-one rugby, and it seems they like what they see.

In turn, greater awareness and visibility of the sport within the States has led to a realisation by players, coaches and even administrators that the Eagles can achieve something on the global stage. Not only is the squad approaching this World Cup with an intensity never before seen but larger goals - such as a professional domestic league and hosting a future tournament themselves - are being discussed.

"I think going way back you thought in the moment more than down the road and the great possibilities," says Tolkin, whose journey as a rugby coach began back in 1986. "Years ago, decades ago, you thought 'OK, we can start attracting better athletes, mainstream athletes, improve the culture of the game and the coaching'. You didn't think about the All Blacks at Soldier Field and Wallabies and doing those things. That has been a massive part of the appeal to people. Seeing us and rooting for us in these great stadiums."

The next step now, of course is to channel the enthusiasm of this new "movement" into something tangible on the pitch. The US won their first ever World Cup match - 21-18 against Japan - but in truth Eagles fans have since been served some pretty meagre gruel.

Tolkin accepts there has been a sea change within the squad, though, as they prepare to start their campaign against Samoa in Brighton on Sunday. More players are playing overseas, and excelling, which in turn changes the culture within the squad as a whole.

Success off the pitch has not yet transmitted itself into results on the pitch, as the recent Pacific Nations Cup showed. But the Eagles were missing one very special ingredient for that tournament in Samu Manoa, and they took solace from the fact Canada and Japan were both dispatched.

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Pool B offers a tough route to the last eight for a tier-two nation, with Samoa, Scotland and Japan standing in their way. But the USA management do not see anything in Vern Cotter's side to worry them. "They have no game-changers," was one member of the camp's assessment of Scotland.

"I think we all understand how difficult it is to win any World Cup game," Tolkin says more soberly. "So, just a singular win is a great achievement. Having said that, though, we know that we are capable of putting in quality performances that can bag us a win. And this would be the first time that we've gone and realistically said: 'Hey, with some really hard work, a couple of good bounces of the ball, we have that opportunity'.

"It's not out of the realm of possibility and we're certainly going to play every game with that overall goal in mind of we can do this with some hard work and a little bit of luck - we have the capable players and athletes."

The USA spent part of their World Cup training camp using the rugby facilities at the Google campus in California. We will soon discover whether they can turn their own brand of blue-sky thinking into a reality that gives their growing fan base something to really get excited about.