2016 Rio Olympic Games in Brazil Aug 05-21,2016 - US women's water polo team prepare to defend their gold medal in Rio

An Olympic event since 1900, water polo has recently been gaining in popularity across the United States but has a long tradition in Eastern Europe, whose national men's teams are perennial medal contenders.

The women's tournament was added to the Olympics in 2000, and reigning world champions the United States have medalled at each Games.

Favourites in Rio, the 13 -member U.S. women have their sights on a second straight gold after beating Spain in the2012  London Olympics Games final with their strongest challengers likely to be Australia, China and Brazil.

Considered one of the world's most demanding sports, water polo has in recent years adopted penalty shootouts instead of extra time to resolve draws.