It’s Andrija Prlainovic and Serbia on the men’s side, and Maggie Steffens and the U.S. for the women’s tournament.

The rest is pretty murky.

The defending world water polo champions are the big favorites for the Rio Olympics, but the top challengers to each country are unclear.

“I think Serbia right now is the favorite and I think everyone else is about even,” U.S. men’s captain Tony Azevedo said. “The Olympics is a funny tournament where it’s one game a lot of times. So you could start off bad and then end strong, or start off great and end terrible. But right now Serbia is definitely the favorites I think and everyone else is just wanting to get there and stay away from them.”

Prlainovic powered Serbia to the world title last August in Russia, winning the MVP award after scoring three times in an 11-4 victory over Croatia in the final. He was named best player of January’s European Championships when he collected 18 goals and 22 assists while helping Serbia to its third straight championship in the tournament, which includes many of the world’s top players.

Serbia also was one of the favorites for London in 2012, but lost to Italy in the semifinals and settled for bronze.