Sienna Green

Early and personal life Green was born in North Sydney, New South Wales, Australia. She is the daughter of former water polo players Tessa and Antony Green; her father represented Australia at the 1989 Maccabiah Games (winning a bronze medal) and the 1993 Maccabiah Games in Israel. She has one older sister, Allie, and one older brother, Zac (who played for the Australian men's U18 water polo team, and plays water polo as a defender for UC Santa Barbara). She became interested in water polo at age nine as she saw it as a combination of her two favourite sports, swimming and basketball. With them, she won the U18 Australian Nationals competition in 2020, and an Australian Water Polo League (KAP7 Cup) title in 2021.

She played in 2023 as a central defender for the University of California, Los Angeles, scoring 39 goals in the team's 29 games. Green was named Association of Collegiate Water Polo Coaches (ACWPC) All-American (Honorable Mention 2023), Mountain Pacific Sports Federation (MPSF) All-Newcomer Team (2023), and ACWPC All-Academic (Outstanding 2023).

At 19 years of age, Green was made the youngest member of the Stingers' 2024 world championships team, and the youngest member of the Stingers ever. She plays for the team as a utility player. She was the youngest Australian woman to compete in Water Polo in the Olympics, and scored three goals in seven games, six of which Australia won.