Which 2023 World Juniors Medalists Have Made International Marks at Senior Level
The last edition of the World Junior Championships was held in 2023, with Netanya, Israel serving as the host. The United States topped the standings with 33 overall medals and 15 gold, followed by Australia with 24 total medals and nine gold. The U.S. and Australia are again expected to be forces at this year’s World Juniors, scheduled for Aug. 19-24 in Otopeni, Romania.
But before this summer’s meet open, let’s look at which medalists from the 2023 World Juniors made a mark on senior competition at the international level. The following medalists from Netanya rode the momentum of their junior success to noteworthy accomplishments at either the 2024 Olympic Games in Paris, or the recently concluded 2025 World Championships in Singapore.
Note: Featured athletes have either finaled in an event at the 2024 Olympics or 2025 World Championships, or helped their country medal in relay competition.
Men
Tomoyuki Matsushita
Japan’s Tomoyuki Matsushita picked up the gold medal in the 400 individual medley at the 2023 World Junior Championships, and he has not slowed down in the ensuing years. Matsushita was the silver medalist in the 400 IM at the 2024 Olympic Games and replicated that finish at the 2025 World Championships. Both of Matsushita’s silver medals came behind Frenchman Leon Marchand.
Flynn Southam
The gold medalist in the 200 freestyle and silver medalist in the 50 freestyle at the 2023 World Juniors, Flynn Southam earned a silver medal in the 400 freestyle relay and a bronze medal in the 800 freestyle relay at the 2024 Olympics in Paris. At the 2025 World Champs, Southam led off Australia’s victorious 400 freestyle relay and opened the bronze-medal 800 freestyle relay. Individually, he was 10th in the 200 freestyle and 12th in the 100 freestyle.
Ed Sommerville
Two years after securing a bronze medal in the 200 freestyle at World Juniors, Ed Sommerville contributed a prelims leg on the Australian 800 freestyle relay that went on to win bronze at the World Championships. In the 200 freestyle, Sommerville just missed advancing to the semifinals with a 17th-place effort in prelims.
Petar Mitsin
A Bulgarian, Petar Mitsin was the world junior champion in the 400 freestyle in Israel, where he was also the silver medalist in the 800 freestyle and 200 butterfly. An Olympian in 2024, Mitsin recently finished seventh in the 400 freestyle at the World Champs.
Kuzey Tuncelli
One of the best-known junior stars in the world, Turkey’s Kuzey Tuncelli captured double-gold in the 800 freestyle and 1500 freestyle at the last Wolrd Juniors. He was fifth at the Paris Games in the 1500 freestyle and placed sixth in the 800 free and 1500 free at the 2025 Worlds.
Zhang Zhanshuo
China’s Zhang Zhanshuo was the bronze medalist in 2023 in the 800 freestyle and 1500 freestyle, in addition to winning silver in the 400 individual medley. That success eventually led Zhang to fifth in the 400 freestyle at the 2025 World Championships, where he also contested the 800 freestyle and 400 IM. At Worlds, Zhang anchored China to the silver medal and an Asian record in the 800 freestyle relay.
Women
Olivia Wunsch
The Australian swept the sprint-freestyle events and was the bronze medalist in the 50 butterfly at the 2023 World Juniors. She represented her homeland at the next year’s Olympic Games, where Wunsch handled a prelims leg on the 400 freestyle relay, which granted her a gold medal when Australia prevailed in the final. More, at the 2025 World Championships, Wunsch anchored Australia to gold in the 400 freestyle relay before illness derailed her individual events.
Milla Jansen
Another Aussie, Milla Jansen was the silver medalist in the 100 freestyle at the last World Juniors. Two years later, Jansen played a key role for the Dolphins at the World Champs in Singapore. She handled the third leg of Australia’s triumphant 400 freestyle relay and contributed a prelims leg in the 800 freestyle relay, which was won by the Aussies in the final.
Anna Moesch
The bronze medalist in the 100 freestyle in Netanya, American Anna Moesch walked away from the 2025 World Champs with a pair of relay medals. The University of Virginia standout saw preliminary duty in the 400 freestyle relay and 800 freestyle relay, both of which resulted in silver medals for Team USA in the finals.
Jamie Perkins
The gold medalist in the 400 freestyle at World Juniors in 2023, Jamie Perkins has emerged into a go-to performer for Australia at the senior level. She earned a gold medal at the Paris Games after racing in the prelims of the 800 freestyle relay. This summer, she was strong at the World Champs, highlighted by helping Australia to gold in the 800 freestyle relay. Perkins also placed sixth in the 400 freestyle and seventh in the 200 freestyle.
Iona Anderson
The gold medalist in the 50 backstroke and silver medalist in the 100 backstroke at World Juniors, Iona Anderson was fifth in the 100 backstroke at the 2024 Olympics. She collected a silver medal in the 400 medley relay due to her prelims effort on the backstroke leg.
Eneli Jefimova
Estonian Eneli Jefimova has competed frequently in international competition at the junior and senior levels over the past few years. Jefimova was a triple-medalist in the breaststroke events at the last World Juniors, including gold in the 50 breaststroke. She was seventh in the 100 breaststroke at the 2024 Olympics and at the 2025 World Champs, Jefimova was sixth in the 50 breaststroke and 10th in the 100 breaststroke.
Mizuki Hirai
A University of Tennessee recruit, Mizuki Hirai snared bronze medals in the 50 butterfly and 100 butterfly at the 2023 World Junior Champs. She was seventh in the 100 fly at the Paris Games and at the 2025 World Champs, Hirai was seventh in the 100 fly and ninth in the 50 fly.
