Learner Tien has stunned the tennis world, claiming an upset victory over Daniil Medvedev at the Australian Open.

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?

Learner Tien has announced himself on the world stage with a huge upset victory over world No. 5 Daniil Medvedev, emerging as a new American tennis star