Last year’s runner-up Daniil Medvedev was dumped out in the Australian Open second round by 19-year-old qualifier Learner Tien in a massive Melbourne shock at close to 3:00 am Friday.In his debut Australian Open, the American ranked 121 stunned the world number five 6-3, 7-6 (7/4), 6-7 (8/10), 1-6, 7-6 (10/7) in a nailbiter and faces France’s Corentin Moutet in the next round.