When rugby returned to the Olympic fold in 2009 via its sevens format, New Zealand's men and women were favourites to replace the United States as the answer to the now 92-year-old trivia perennial: 'Who are the defending Olympic rugby champions?' With five weeks until the tournaments start and the announcement of the national squads tomorrow, such a premise seems less convincing. Olympic inclusion has increased worldwide investment in the game, and countries have loomed en masse into medal contention. In the men's world series this season, six nations - New Zealand (three), Fiji (three), South Africa, Kenya, Samoa and Scotland - won tournaments. Argentina and England featured in finals and the US and France in semifinals. Nine of those candidates will feature in Rio. Samoa are absent after Spain beat them in qualification, and England and Scotland combine as Great Britain. Australia (three), England and Canada triumphed at the women's world series tournaments. New Zealand, France and Russia featured in finals. Of those, only Russia failed to make the Olympic cut. Former national sevens representative Karl Te Nana observed both seasons as a TV commentator. He says the congestion of medal contenders has diluted New Zealand chances. "The standard has got better, including five different winners from the last five [men's] tournaments. "Take Kenya, who won their first tournament in Singapore. Sevens suits their athleticism. They're big, strong, fast and love the heat. They've made their biggest strides over recent years in the contact area. They used to get intimidated, but former coach Mike Friday [now mentoring the US] changed their approach." Te Nana says the men's side have suffered more injuries than ever on their way to third this season, which took out Scott Curry, Tim Mikkelson, Joe Webber, Sonny Bill Williams, Sam Dickson, Sherwin Stowers and Ben Lam at various stages. "That's basically a starting seven, but to remain in contention to win in the final tournament is still an achievement," Te Nana says. "If we have our frontline players, we'll be a threat, like we saw with wins in Wellington, Sydney and Vancouver. "The area to sharpen up is the breakdown. That's where Fiji [winners in the past two seasons] have been so dominant. They can make multiple turnovers. If we get our hands on the ball, which has been an issue with the likes of Curry and Dickson injured, we've got the backs to finish." The indications are most of the first choice team are available. The women's side face similar issues. In 2014-15, they won their third consecutive world title. Now they are chasing Australia. Former Black Fern Melodie Robinson told She's Got Game last week that Australian coach and former sevens captain Tim Walsh is the catalyst in the momentum shift. "He is an astute rugby brain. Three years ago, he cleaned out the Australian squad and brought in a host of 16, 17 and 18-year-olds, most of whom came from other sports. Many had a good background in touch rugby. They were quite small but fit with massive skill levels. "He plays a style of sevens which spreads the ball wide, whereas New Zealand has gone back to an offloading game. I like their [the Australian] style better, so they're gold medal prospects for sure." Robinson says the most crucial New Zealand player is Tyla Nathan-Wong. "She is the most accurate conversion taker in the world and her sweeping defence is unbelievable. They do have cover, but she is world class." Te Nana says one disadvantage to the New Zealand women's programme is a relative lack of centralisation. "By doing that, these other teams have caught up. On paper, we've got the best athletes, but they go away to provinces and train individually for weeks before getting together in camp again. They only tend to merge a couple of weeks at a time. "For example, if I go for a run, I won't push myself as much as if there was a team there. Centralisation offers a better chance to get the combinations and vibe going." Regardless of whether that issue is resolved long term, it will do little to impact the pending Olympic result from here.