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,

The Irvine native and 19-year-old qualifier, who played one semester at USC, wins a 4-hour, 49-minute thriller that ends at nearly 3 a.m. in Melbourne

American qualifier Learner Tien shocked the tennis world on Thursday when he upset last year's Australian Open runner-up Daniil Medvedev in a nearly five-hour, five-set match in the second round. Tien took an early two-set lead (6–3,