By Ian Ransom MELBOURNE (Reuters) -Teenage qualifier Learner Tien became the youngest man to reach the Australian Open fourth round in 20 years as the future of American tennis lit up Melbourne Park on Saturday.

At the age of 19, Learner Tien defeated Daniil Medvedev in a five-set thriller that finished just before 3 a.m. in Melbourne.

The 19-year-old American upset fifth-seeded Daniil Medvedev in a five-set Australian Open marathon that lasted nearly five hours.

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

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?

American qualifier Learner Tien became the youngest man to reach the Australian Open fourth round in 20 years as he beat an ailing Corentin Moutet 7-6(10) 6-3 6-3 on Saturday, continuing the teenager's fairytale run at Melbourne Park.

American teenager Learner Tien on Saturday became the youngest male player to reach the fourth round of the Australian Open since Rafael Nadal in 2005. The 19-year-old southpaw beat unseeded Frenchman Corentin Moutet in straight sets,