Learner Tien, a 19-year-old from California, became the youngest American man to reach the Australian Open's third round since 1990, upsetting No. 5 Daniil Medvedev in five sets.

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

By Ian Ransom MELBOURNE (Reuters) -Teenage qualifier Learner Tien became the youngest man to reach the Australian Open fourth round in 20 years as the future of American tennis lit up Melbourne Park on Saturday.

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

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

Two friends from California, Learner Tien and Alex Michelsen, have both reached the fourth round at the Australian Open