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

The outcome was eyebrow-raising because of the wide gulf in experience and accomplishments between the two players at Margaret Court Arena.

American teenager Learner Tien produced arguably the biggest shock of the Australian Open so far as he defeated last year’s runner-up Daniil Medvedev in five sets, 6-3, 7-6 (4), 6-7 (8), 1-6, 7-6 (7).