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 outcome was eyebrow-raising because of the wide gulf in experience and accomplishments between the two players at Margaret Court Arena.

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 a racket-tossing Daniil Medvedev 6-3,