By Matt Slater and Gordon Farquhar
Rugby-loving Olympic boss Jacques Rogge has said the sport's shorter version, sevens, faces "an uphill battle" in its bid to gain a place at the Games.
Rogge, a surgeon and Olympic sailor, won 10 Belgian rugby caps
Rogge, who played rugby for Belgium, says the 15-a-side game has no chance of Olympics status and sevens faces stiff competition from other sports.
He also told BBC Sport rugby union's bosses should act to improve the sport.
"It was a good World Cup in terms of the public attention, but I'm not happy
about the quality of play," he said.
"I am passionate about rugby but I think that the game has to evolve to keep its appeal. Defence has taken precedence over attack.
"(At the Rugby World Cup) play went from one maul, to another maul, to another maul, waiting for a penalty to be blown.
"I think the law-makers have to think about making the game more open, probably by working on a quicker liberation of the ball in rucks."
The International Olympic Committee president, who sailed in three Olympics for Belgium but says he always preferred rugby, is thought to be sympathetic to rugby sevens' Olympic case.
Sevens was one of five sports put to an IOC vote in 2005 for inclusion at London 2012 but failed to win enough support to gain admittance.
The fast-paced game was up against golf, karate, roller sports and squash for one of two spots in the Olympic programme freed up after baseball and softball were voted out.
But sevens was knocked out after three rounds of voting, and the two sports that advanced to the final stage of the process, karate and squash, both failed to win the two-thirds majority needed for inclusion in the Olympic line-up.
Unlike football, you cannot play rugby every third day
Rugby, which has appeared in four Olympic Games with the USA winning the last gold medal in 1924, took the setback badly, particularly as the sport had earned high marks for its potential popularity.
Speaking at the time of the 2005 vote, the then-president of the International Rugby Board, Dr Syd Millar, said the IOC had missed a "golden opportunity to modernise the Olympic programme".
The IRB maintains that rugby union is played in over 100 countries and a sevens tournament would be relatively cheap and straightforward to run.
"In terms of broadcast, commercial and ticket sales opportunities, the IOC's own evaluation process [has shown] that rugby sevens is among the top five in comparison to the existing Olympic sports," Millar added.
The format's potential was confirmed at the 2006 Commonwealth Games in Melbourne, where record crowds watched New Zealand pip England to the gold, with the highly-fancied Fiji having to settle for bronze.
England's Mathew Tait starred at the 2006 Commonwealth Games
Fiji, and its Pacific neighbours Samoa and Tonga, would be serious contenders for medals in an Olympic sevens tournament, a fact that Rogge admitted was an attractive element of the sport's appeal.
"The top is far broader in sevens (than in the 15-a-side format), and you don't have the huge margins of victory you get in 15s; that would be good for the Olympic tournament," he said.
The 55-year-old, however, completely ruled out 15-a-side rugby as an Olympic sport on the grounds that the recovery time between matches is too long.
"Unlike football, you cannot play rugby every third day. The Olympics are only 16 days long so 15s are not an option," he said.
"Sevens could be. It is definitely a candidate. But there are other sports that want to join the programme, so let's wait and see."