Learner Tien produced a stunning display to outlast three-time Australian Open finalist Daniil Medvedev in an enthralling four-hour, 49-minute second-round clash.

Tien emerged a 6-3 7-6 (7-4) 6-7 (8-10) 1-6 7-6 (10-7) victor, becoming the youngest American man to reach the tournament's third round since Pete Sampras in 1990.

After conceding an early break, Tien roared back against the world number five, winning five games on the spin before closing out the opening set with a love service game.

The second set saw four consecutive breaks of serve, but Tien would again prevail, emerging victorious in the tie-break to go within touching distance of a memorable triumph.

Medvedev, however, remained composed in the face of adversity, trading blows with his opponent in an over hour-long third set before winning another tie-break to stay alive.

The fourth set was more straight forward for Medvedev, taking just 26 minutes to dispatch Tien to take the enthralling encounter the distance at Melbourne Park.

A frustrated Medvedev missed three chances to take an early break in the final set, with a six-minute delay with the set level at 5-5 allowing him to regain his composure.

Medvedev was able to win a crucial 11th game, giving himself the chance to serve for the match, but Tien broke back, then held his nerve to earn a famous victory in the first-to-10 tie-break.

Remember the name: Learner Tien@wwos • @espn • @eurosport • @wowowtennis • #AusOpen • #AO2025 pic.twitter.com/HQmCNDMd5J
— #AusOpen (@AustralianOpen) January 16, 2025

Data Debrief: Learner becomes teacher

Tien arrived at Melbourne a relatively unknown player, but he will leave with a notable scalp on his tennis CV, whatever happens in the next round.

He became the first qualifier to claim an ATP top-five win at the Australian Open since Guillermo Garcia Lopez, who defeated Carlos Moya in 2005 (R128).

Since 1973, this year's Australian Open is only the third grand slam event where three teenagers (Joao Fonseca, Jakub Mensik and now Tien) have claimed ATP top-10 wins after Roland-Garros in 1990 and 2006.

Medvedev has now played a five-setter in his last five matches at the Australian Open, equalling the longest such streak in the Open Era (five by Paul Annacone, Jim Courier, Nicolas Lapentti and Alexei Popyrin). This time, he was unable to stay the course.