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,

Learner Tien pulled off a massive upset against Daniil Medvedev at the Australian Open. So, who is Tien, the 19-year-old out of California?

At the age of 19, Learner Tien defeated Daniil Medvedev in a five-set thriller that finished just before 3 a.m. in Melbourne.