Learner Tien, an American teenager, defeated Daniil Medvedev, the runner-up from the previous year, in five sets, 6-3, 7-6 (4), 6-7 (8), 1-6, 7-6 (7), in what may have been the biggest upset of the Australian Open thus far.
The less seasoned 19-year-old won the final-set tiebreak to secure the biggest victory of his young career as the cruel, draining match came to an end just before three in the morning in Melbourne.
In the third set, Tien, who was playing in the second round of a grand slam for the first time, had a chance to win the match with a match point when Medevedev made a stunning comeback.
In Melbourne, it appeared that the fifth-seeded Russian would have the momentum to win a second straight five-set victory.
