Rugby will return to the Olympic program after a 90-year gap when the second summer Youth Olympic Games open on Saturday in Nanjing, Jiangsu province.

The 15-a-side version was played in the early years of the Olympics, but it was dropped after the 1924 Games.

In 2009 the International Olympic Committee voted to re-admit the sport in its seven-a-side form, and it will be played at the 2016 Games in Rio.

The Nanjing youth event will be the first time rugby sevens has appeared on the Olympic program, and there will be six men's and six women's teams.

"The sevens game is exciting and fun, easy to watch and understand and will be a great attraction at the Olympic Games," Jean de Villiers of South Africa, winner of the 2007 Rugby World Cup, told the International Rugby Board website.

"Rugby sevens has become one of the most exciting spectacles on the annual sporting calendar, and, while the game has grown around the world, the competitiveness of the various countries competing on the sevens circuit has exploded."

Rugby sevens is sanctioned by the IRB and mostly follows the same rules as the 15-player game.

Argentina, Fiji, France, Japan, Kenya and the United States will take part in the men's competition in Nanjing, while Australia, Canada, China, Spain, Tunisia and the US will compete in the women's event.

There will be an initial round-robin stage where teams will compete twice a day. Three points will be awarded for a win, two for a draw and one for a defeat. The top four teams from the group stage will make the semifinals.

The matches will consist of two halves of seven minutes. Scoring occurs more frequently than in the full version as the defenders are more spaced out on the field.

"Sevens is a highly skillful sport, hugely physically demanding and I truly think that it deserves to be part of the Olympics," Sue Day, a former captain of England's sevens team, told the IRB website.