Green To Cardinal

STANFORD, Calif. – Sienna Green, a 2024 Olympic silver medalist and 2023 ACWPC Honorable Mention All-American at UCLA, has transferred to Stanford for the 2026 campaign, as announced Wednesday by Dunlevie Family Director of Women’s Water Polo John Tanner.

Green boasts extensive international experience as a member of the Australian National Team, culminating with a silver medal at the 2024 Paris Summer Olympics. Green, who started all seven games at defender as Australia won its first six games before falling to Spain in the gold medal match, captained the national under-18 team and made her debut with the Aussie Stingers in March 2022 during a match against Canada. Green is the youngest water polo player to represent Australia at the national team level and the youngest Australian water polo Olympian.

“We are extremely excited to have Sienna joining our team and program,” said Tanner, who in 28 seasons has guided the Cardinal to 10 NCAA titles and was named ACWPC Coach of the Year for the ninth time in 2025. “As someone who has performed superbly in global and domestic water polo and in the classroom, she will be a wonderful addition to the Stanford community. Sienna is poised, determined and skillful in all phases of the game, bringing a wealth of experience against the world’s best on the world’s biggest stage. Sienna will be a fantastic fit with Stanford, Stanford Water Polo and the world-class women in our program.”

“I’m incredibly excited to begin this next chapter on The Farm and continue both my academic and athletic journey within such a world-class program”, said Green, who helped lead UCLA to a semifinal finish in 2025. “It’s truly an honor to be part of the incredible community and rich legacy of Stanford Water Polo. Stanford fosters an environment of excellence, and I look forward to contributing to that culture both in and out of the pool. In the classroom, I am excited to further my passion for economics, while continuing to grow and challenge myself as an athlete. This is a once-in-a-lifetime opportunity that will push me to grow as a player, student and person while preparing me to thrive long after college.”

Prior to taking the 2024 season off to train and compete with Australia leading up to the Paris Summer Olympics, Green completed a successful freshman season with the Bruins in 2023. Green was named an ACWPC Honorable Mention All-American, ranking third on the team in goals (39) and fourth in drawn exclusions (15) while appearing in all 29 games. Green, who produced nine multi-goal games and four hat tricks, was also named to the MPSF All-Newcomer Team.

A native of Mosman, Australia, Green has been a mainstay for the Australian national team and will be competing for the Aussie Stingers later this week when the World Aquatics Championships get underway in Singapore. Among her international experience, Green served as captain and was the team’s leading scorer at the 2022 FINA World Youth Water Polo Championships in Belgrade, Serbia. She was selected for the Stingers’ 2024 World Championship squad, playing in all seven games and scoring nine goals as Australia finished sixth at the Doha tournament.

Green completed her high school career at SCEGGS Darlinghurst and played club ball for Sydney University. A member of Junior and Youth Australian squads since 2018, Green won the Australian Water Polo League (KAP7 Cup) in 2021 and the U18 Australian Nationals competition in 2020 with the Sydney Uni Lions.

Green is Stanford’s second transfer in as many seasons, as Juliette Dhalluin made an immediate impact in her 2025 debut on The Farm after transitioning from her freshman season at Arizona State in 2023. Earning the second ACWPC All-America honor of her career, Dhalluin was one of Stanford’s most consistent performers and ranked third on the team in assists (36) and fourth in goals (41), shots (77) and multi-goal games (11). A member of the France national team who also competed at the 2024 Paris Summer Olympics, Dhalluin scored seven goals in NCAA competition, including a hat trick in Stanford’s championship game victory over USC.

Stanford (25-1, 5-1 MPSF) claimed its 10th NCAA title overall in 2025 and third over the last four seasons, defeating USC 11-7 in Indianapolis. The nation's only program to have participated at every NCAA Championship since the event's inception, Stanford put the finishing touches on a dominant campaign. In addition to producing one of only four 15-0 starts in school history, the Cardinal recorded three wins apiece against fellow contenders USC and UCLA while holding the nation’s No. 1 ranking for most of the season. Stanford captured both the NCAA and MPSF crowns in the same season for the fourth time in school history (2025, 2023, 2022, 2014).