Teenage Californian Tien took the opening two sets of his second-round match against former US Open champion Daniil Medvedev.

Learner Tien pulled off a massive upset against Daniil Medvedev at the Australian Open. So, who is Tien, the 19-year-old out of California?

Learner Tien has become the youngest American man to reach the Australian Open’s third round since Pete Sampras in 1990

Watch the match highlights between Learner Tien & Daniil Medvedev in Round 2 of the 2025 Australian Open Men's Singles Tournament Tennis.

The 19-year-old who was a late qualifier to the Grand Slam secured the biggest win of his young career on Thursday

Learner Tien, a 19-year-old qualifier from California, notched the biggest upset of the 2025 Australian Open to date by beating 2024 finalist and No. 5 seed, Daniil Medvedev in five sets, 6-3, 7-6(4),