Carlin Isles© Photo by Christopher Lee/Getty Images

Four-time Olympic champion Michael Johnson says the scrappy, "refuse-to-fail" attitude of athletes who have switched from traditional American sports to rugby could make the USA Sevens team a force in Rio next year.

Perry Baker, who played college football for Fairmount State University, and former Detroit Lions triallist and track athlete Carlin Isles are two of the likely stars of the side who typify the mindset Johnson claimed was essential.

"USA Rugby has done a superb job to identify those athletes who have the competitiveness and scrappiness who just refuse to fail," said Johnson, who has taken on the role of mentoring the Olympic rugby team. "Maybe they haven't made in another sport but they refuse to give up. Carlin Isles is someone like that and that attitude is key in the Olympics.

"They will find that it's going to be a challenge and an opportunity to prepare for the Olympic Games. Preparation is everything; it is truly a once-in-a-lifetime opportunity. The U.S. team has done so well sourcing athletes from different sports and that is extremely important.

"That has brought a new focus on rugby in the USA and especially at the grassroots level. I will try and relay to them some of my experiences at the Olympics."

Isles was dreaming of Olympic gold at London 2012 before turning his attention to Sevens, having run the 100 metres in 10.24 seconds. The lure of team glory saw him leave sprinting prior to the trials for the Games that year, but his speed has made him a favourite on the Sevens circuit.

Ironically, after switching to a team sport, Isles has been singled out as something of a poster boy for Sevens rugby in the U.S. as the sport has grown. And Johnson predicted it would become even more popular as a result of the Olympics.

© (Photo by Chris McGrath/Getty Images)

"It is a tremendous opportunity for rugby and for the athletes taking part," Johnson added after it became the country's fastest growing sport in participation terms.

"The Olympics is the pinnacle; there is no higher honour for athletes. These athletes now have that opportunity and it will be challenging to maintain the focus.

"What we've seen in the grassroots level is that participation is growing at an unprecedented level. Not everyone can play basketball or baseball and parents are looking for other opportunities for their children and I think rugby can become a nationwide leader in developing athletes of the future."

The USA Sevens team are due to compete in the first leg of the 2015-16 HSBC World Sevens Series kicks off this weekend in Dubai, but World Rugby's chief executive Brett Gosper already has one eye on the opportunities offered by the Olympics.

"There is a growing interest in the USA as it is the fastest growing team sport in with over a million participants," Gosper said. "There is also a higher level of female participants so there is huge interest there.

"There is a regional Pro League launching early next year and there is the Las Vegas Sevens tournament, which continues to have a lot of interest. There is lots on that programme to create interest in rugby in the USA.

"It is a key development market for us and it is growing in salience and interest in that market, which is great for us in the future."