Learner Tien

Learner Tien (born December 2, 2005) is an American professional tennis player. He has a career-high ATP singles ranking of world No. 23 achieved on February 9, 2026, and a best doubles ranking of No. 343 reached on August 18, 2025. His best achievement is reaching a major quarterfinal at the 2026 Australian Open. He is currently the No. 3 American in men's singles.

Tien has won one ATP Tour singles title at the 2025 Moselle Open, as well as the 2025 Next Gen ATP Finals.

Early life

Tien was born on December 2, 2005, in Irvine, California, to parents Khuong Dan Tien and Huyen Tien, Hoa refugees who fled South Vietnam to the United States. Tien is a second-generation immigrant of Vietnamese descent.

He started taking tennis lessons in his early childhood, at a tennis facility next to his home. Tien's potential was noticeable from the start, as he won his first tournament at the Racquet Club of Irvine at the age of 5.

Junior career

Tien had successful results on the ITF junior circuit, maintaining a 76–23 singles win-loss record and reaching two major finals, at the 2023 Australian Open and the 2023 US Open.

In doubles, he compiled a 36–18 win-loss record and won the 2023 Australian Open, with countryman Cooper Williams. It culminated in an ITF combined ranking of world No. 4 on February 20, 2023.

Junior Grand Slam singles results

Australian Open: F (2023)
French Open: SF (2023)
Wimbledon: QF (2022, 2023)
US Open: F (2023)

Junior Grand Slam doubles results

Australian Open: W (2023)
French Open: QF (2023)
Wimbledon: 2R (2022)
US Open: 2R (2022)

Professional career

2022–2023: Junior National champion, major debut

At 16 years old, Tien graduated high school and won the 2022 USTA Boys 18s National Championship, which earned him a wildcard into the main draw of the 2022 US Open, making him the youngest player to compete in the men’s singles main draw at the US Open since a then-16-year-old Donald Young (also the champion at Kalamazoo) played in the 2005 US Open, and also the first player aged 16 to compete since Zachary Svajda in 2019. He lost in four sets to 32nd seed Miomir Kecmanović.

In August 2023, he received another wildcard to the 2023 US Open, which was his second major appearance. He lost to fellow countryman and tenth seed Frances Tiafoe in the first round.

2024: First Challenger title & ATP quarterfinal

In July, Tien also received a wildcard for the 2024 Cranbrook Tennis Classic in Bloomfield Hills, Michigan where he lifted his maiden Challenger title. He became the youngest American Challenger champion since 2016, when an 18-year-old Frances Tiafoe won in Granby, Canada. He also won the M15 in Lakewood, California, increasing his winning streak to 25. At the end of July, a week later, he again made the quarterfinals at the 2024 Chicago Men's Challenger and reached the top 250 in the rankings on July 29, 2024. He reached his second Challenger semifinal of the season, defeating eight seed Hong Seong-chan. He lost to Yunchaokete Bu, ending a 28-match winning streak across ITF and ATP Challenger tournaments. A week later, he also made the quarterfinals at the 2024 Lexington Challenger but lost to Hugo Grenier.

Tien secured a main draw wildcard for the US Open by winning the US Open wildcard challenge. Ranked No. 231, Tien qualified for the main draw at the 2024 Winston-Salem Open. There he defeated fellow qualifier Tristan Schoolkate and upset ninth seed Fábián Marozsán and Thiago Seyboth Wild to record his first three ATP Tour wins and reach his first ATP quarterfinal. He became the youngest American ATP tour-level quarterfinalist since Brandon Nakashima in 2020 (in Delray Beach). As a result he climbed 40 positions in the singles rankings to world No. 191 on August 26, 2024.

Tien won his second Challenger title in Las Vegas, defeating Tristan Boyer, and moved up another 40 positions in the singles rankings to a new career-high of No. 151 on September 16, 2024. He reached the top 125 in the rankings at world No. 124 on October 14, 2024, following another title at the Fairfield Challenger after playing a 39-minute final, the shortest championship match in Challenger history, against Bernard Tomic. He became the fourth American to win three ATP Challenger Tour titles before his 19th birthday after Taylor Fritz, Andy Roddick and Sam Querrey. As a result, on November 26, 2024, at 18 years old, Tien qualified for the 2024 Next Generation ATP Finals.

2025: Australian 4th round, Next Gen champion

Ranked No. 121, Tien made his Australian Open debut after qualifying into the main draw. He defeated Camilo Ugo Carabelli in the first round for his maiden Grand Slam win. Next, he upset fifth seed Daniil Medvedev, for his first top 10 and top 5 win, after winning the 10-point tiebreaker in the fifth set, in a 4 hours and 50 minutes match that ended at 3 am in Melbourne. At 19 years old he became the youngest American player to reach the third round of the tournament in 35 years, since Pete Sampras in 1990. Tien defeated Corentin Moutet in straight sets to reach the fourth round of a major for the first time in his career and moved into the top 100 in the singles rankings. With the win, he became the second-youngest American man to reach the fourth round at the Australian Open in the Open Era (after Sampras), and the youngest player since Rafael Nadal in 2005. His run ended with a loss to Lorenzo Sonego, in four sets.

At the Mexican Open he qualified for the main draw and defeated top seed and world No. 2 Alexander Zverev, recording his biggest win by ranking, to reach his first ATP 500-level quarterfinal. He became the youngest American man to beat a Top 3 player since 2001, when Andy Roddick, who was 18 years old at the time, defeated a No. 1-ranked Gustavo Kuerten in the third round of the Canadian Open. He was also the youngest man since 2022 to defeat a No. 3-ranked Zverev in the Madrid final, when Carlos Alcaraz, a younger 19 at the time, did it. As a result he moved into the top 70 in the singles rankings on March 3, 2025.

Tien reached the fourth round of an ATP 1000 for the first time in his career, at the Canadian Open, upsetting 22nd seed and local favorite Denis Shapovalov en route. He became the youngest American to reach the round of 16 at the Masters level since a 19-year-old Frances Tiafoe in 2017 Cincinnati.

Tien won his first ATP Tour title at the Moselle Open after defeating Cameron Norrie, reaching the top 30 at world No. 28 on November 10, 2025. He also became the first American teenager to lift an ATP trophy since Andy Roddick, in 2002.

2026: Australian Open quarterfinal, top 25

Tien began his 2026 season at the Brisbane International. He was the eighth seeded player at the tournament, but was defeated in the second round by Alex Michelsen. He then went on to play in the Australian Open, where he faced Daniil Medvedev in the fourth round, in a rematch from the previous year's Australian Open. He once again achieved an upset victory, this time defeating Medvedev in straight sets, with the second set being the first time that Medvedev has ever lost a set 6–0 at a major. With this victory, he reached his first Grand Slam tournament quarterfinal, and became the youngest man to reach an Australian Open quarterfinal since 2015. Despite losing in the quarterfinal to Zverev, this achievement placed him in the top 25 of the men's singles ranking for the first time in his career.