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,

The 19-year-old who was a late qualifier to the Grand Slam secured the biggest win of his young career on Thursday

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.