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

Daniil Medvedev ripped 24 aces and converted six break points to outlast Kasidit Samrej in a 3-hour, 8-minute first-round victory Tuesday at the 2025 Australian Open. No. 9 Andrey Rublev was the latest upset victim.

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

American teenager Learner Tien produced arguably the biggest shock of the Australian Open so far as he defeated last year’s runner-up Daniil Medvedev in five sets, 6-3, 7-6 (4), 6-7 (8), 1-6, 7-6 (7).

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

Learner Tien, a 19-year-old qualifier from California, became the youngest American man to reach the Australian Open's third round since Pete Sampras in 1990, upsetting Daniil Medvedev in five sets 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),