American teen Learner Tien pulled off the biggest upset so far at the 2025 Australian Open, ousting Russian Daniil Medvedev -- the No. 5 player in the world -- in a 4-hour, 49-minute thriller at Margaret Court Arena.

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

World No. 5 Daniil Medvedev has been fined more than US$76,000 for two separate incidents which occured during his first and second-round matches at the Australian Open.