Rugby World Cup may expand in 2023, says governing body
World Rugby boss Brett Gosper has said a future World Cup could enlarge the number of teams taking part without losing competitiveness.
Both England 2015 and Japan 2019 will have 20 teams, but 2023 may be larger.
Mr Gosper said allowing fringe nations into the event would allow them "to promote the sport in their countries".
"As the sport grows and we conquer new markets the discussion is about looking towards expanding [of the World Cup], rather than contracting," he added.
A larger World Cup would offer the chance to sell the sport into new markets, as well as increasing the potential revenues from the tournament in terms of TV deals, sponsorship, hospitality and ticket sales.
He said a larger World Cup would not necessarily mean teams playing more games, as tournament groups - which currently have five teams in them - could be juggled in size.
Mr Gosper said rugby union was growing strongly around the globe, but particularly in the markets of the US, China, India and Mexico, with Russia and Germany also growing nations.
"Rugby is the fastest growing team sport in the USA," Mr Gosper told a Sport Industry Group Breakfast Club gathering of sporting executives in London.
He added that although Germany and Russia also offered potentially huge new TV markets for the sport, 2019 was not considered the right time to expand and bring them in.
Meanwhile, tag rugby and Sevens were also bringing new players to the game, including women. "We are in very good shape, in all formats, around the world."
Also looking ahead to the 2023 World Cup, he said that there would be moves to "outlaw" secondary ticketing - that is the resale of tickets for, often huge, profit - at that event.
There is no legislation to stop such reselling at this year's World Cup, but 2015 organisers have said new legislation forcing secondary websites to publish the exact row and seat number would prove a deterrent, as people buying tickets from unofficial sources could be refused entrance.
Mr Gosper also said that World Rugby was still considering whether to ban players at the 2015 event from using mobile phones on match days during the World Cup as a preventative measure against match-fixing, as well as to "provide security and peace of mind".
He said that any strategy involving communications at the event also had to take on board the human factor of allowing players to have contact with their families.
Meanwhile, Mr Gosper said the build-up to RWC 2015 was going smoothly, with no major concerns, but a focus that "everything that needs to be done is done".
"I am not saying things can't go wrong, but they are certainly on track."
He said the reason for rebranding of what had been the IRB - the International Rugby Board - as World Rugby had been to promote "what the brand stood for" and "increase comprehension".
He said many people had not heard of the IRB, while those that had thought it was just a decision-making body, rather than also being the lead body in promoting and nurturing the sport.
The organisation is also working with sports technology firm Hawkeye about how to better enhance the fan experience inside the stadium.
Mr Gosper attracted recent controversy over a tweet saying that he did not want England to fail to get through its 2015 World Cup group stage, much to the annoyance of group rivals Wales.
The Australian, a former professional player, said that he was merely making a point that global sports tournaments have a more intense atmosphere if the host nation makes progress.
"There's no reliance by the tournament on England's success or not," he added, saying the 2015 World Cup would be a financial and sporting success event if England went out at the group stage.