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,

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 Thursday.