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,

Daniil Medvedev has copped a pair of hefty fines following his surprise Australian Open exit. The world No. 5 was bundled out in the second round by qualifier Learner Tien – arguably the biggest upset of the tournament thus far.

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?