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,

American qualifier Learner Tien became the youngest man to reach the Australian Open fourth round in 20 years as he beat an ailing Corentin Moutet 7-6(10) 6-3 6-3 on Saturday, continuing the teenager's fairytale run at Melbourne Park.

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 celebrated his shock Australian Open victory over three-times runner-up Daniil Medvedev in true teenage fashion, seeking out a well-earned pizza after edging a five-set thriller to progress to the third round.

Learner Tien, 19, became the youngest American man to reach the Australian Open's third round since Pete Sampras in 1990.