The final match of the day saw American Learner Tien, playing in his first major outside of the U.S. Open, upset No. 5 seed Daniil Medvedev in a five-set classic, 6-3, 7-6, 6-7, 1-6, 7-6, that ended at 2:54 a.m. local time. Medvedev had reached three of the past four Australian Open finals, but could not fend off a ferocious Tien.

Defending champ Jannik Sinner drops set for first time since October, but rallies for win; American Danielle Collins plays villain while advancing.

Jannik Sinner has announced that he will part ways with his coach Darren Cahill at the end of the season. The Australian, who joined Sinner's team in July 2022, will conclude the 2025 campaign before stepping back from full-time tennis.

Highlights of the fifth day of the Australian Open on Thursday (all times GMT): 1554 TEENAGER TIEN STUNS MEDVEDEV American qualifier Learner Tien held his nerve in a battle that lasted four hours and 49 minutes to stun Russian fifth seed Daniil Medvedev,