There are three American men aged 23 and under in the second week of a Grand Slam. That hasn't happened since 2003

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

Two of four American men still playing in Melbourne, Irvine native Tien, 19, and Aliso Viejo native Michelsen, 20, became friends on the youth tennis circuit

Learner Tien won again at the Australian Open today, knocking out France’s Corentin Moutet to progress to the fourth round of the men’s singles.

Learner Tien and Alex Michelsen were born about 15 months apart and first crossed paths a decade ago when they were playing in Southern California tennis tournaments for kids. Tien, now 19, and Michelsen,

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