Corona del Mar High twin seniors Stephania and Ioanna Haralabidis hope to help the Sea Kings win the CIF Southern Section Division 1 girls' water polo title in February.

But over the weekend, the transfers from Greece earned another big title — and a gold medal.

The Haralabidis sisters helped Greece's youth national team win the inaugural FINA Youth World Championships in Perth, Australia. Greece beat the United States, 8-3, in the semifinals before topping Hungary, 9-5, in the championship match on Sunday.

Stephania Haralabidis scored three goals in the title match, and the lefty tied for the team lead with 16 goals in the tournament. Ioanna Haralabidis scored once in the title match, and 11 times in the tournament.

Team USA, which featured Newport Harbor High alumna Maddy McLaren, CdM senior Cassidy Papa and Newport Harbor sophomore goalie Carlee Kapana, finished fourth after a tough 13-12 loss to Russia in the bronze-medal match.

McLaren, the 2012 Newport-Mesa Player of the Year who is now at UCLA, scored five goals in the six-match tournament. Papa, who was team captain, had three goals. The United States finished 3-3 in the tournament.

"We were up by three [against Russia] going into the fourth quarter," said Papa, who returned to the CdM pool deck on Tuesday. "But overall, cool experience, for sure. It was very fun, because there were so many teams. It was very interesting to see the dynamics of every team. And we were in dorms with Romania's boys' team, the Uzbekistan girls and boys. It was super-random, everyone was together."

Papa said it was funny to compete against her CdM teammates, Stephania and Ioanna.

"I know how they play so well and their style," Papa said. "I was like, 'Wow, it's just a bunch of them put onto one team!' Greece was definitely the hardest team, I think, to play, just because they have such a unique style of play. But it was fun. I was up against Stephania for a little bit. I got to see their final game too, and they both played really well."

As team captain, Papa exchanged flags with the other countries during introductions. She brought home pendants from all of the countries that the U.S. played.

"From [training in] Hungary beforehand and New Zealand, I'm seeing a bunch of familiar faces now," she said. "I'm starting to get to know the captains of the other teams. It's an honor."

Papa said that she received updates from Australia on CdM's season-opening games in Santa Barbara last weekend. The short-handed Sea Kings, the top-ranked team in Division 1, went 2-0, including a big victory over No. 3 Santa Barbara.

"I was so excited," Papa said. "I was kind of bragging to everyone that was there a little bit. Luckily, there were no Santa Barbara or Dos Pueblos girls, because I was like, 'Yeah, CdM!' It just made me that much more excited to come back and be a part of it."

Papa, who has signed with Stanford, will resume practicing with CdM and prepare for the Sea Kings' next match, the Battle of the Bay against rival Newport Harbor on Dec. 21 at CdM. The USC-bound Haralabidis sisters are ineligible to compete for CdM until after Dec. 31, per CIF Southern Section transfer rules.

The U.S. men's youth national team, featuring CdM senior Reid Chase and coached by former Newport Harbor coach Jason Lynch, finished eighth at the FINA Youth Worlds. They were edged by Australia, 5-4, in the seventh-place match.

Chase scored seven goals in the tournament for Team USA.

matthew.szabo@latimes.com

Twitter: @mjszabo