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?

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

Daniil Medvedev earns code violation for racket abuse before rallying past wild card entrant; Taylor Fritz carries U.S. banner forward.