In ATPTour.com’s new series, Sliding Tour Moment, a host of top players reflect on a career defining experience, one that they look back on as pivotal in their journey through tennis. This week, Learner Tien recalls his stunning five-set victory against Daniil Medvedev at the 2025 Australian Open.
Learner Tien has been a regular presence on the ATP Tour for barely 20 months. Yet the American lefty has already packed in plenty of memorable moments to the early chapters of his top-level tennis story.
The list of achievements racked up by the 20-year-old Tien since the start of 2025 includes winning two ATP 250 titles (in Metz in 2025 and Geneva in 2026), triumphing at the 2025 Next Gen ATP Finals, and reaching as high as No. 15 in the PIF ATP Rankings. Like any player aiming to push further towards the top of the game, Tien accepts that his progress hinges on relentless hard work and day-to-day consistency, but that does not mean he cannot recognise the significance of certain successes as they arrive.
“I can think of a couple of moments, a couple of matches and maybe periods in my career so far where things have been significant,” Tien told ATPTour.com when asked for any ‘journey-defining’ highlights so far. “I would say [particularly] beating Daniil [Medvedev] in Australia in 2025. I broke the Top 100 off of that, and it was my highest-ranking win at the time. So that was very big for me. I guess it was a big ranking accomplishment, and it was a big confidence boost for sure.”
Tien arrived in Melbourne at the start of 2025 off the back of a breakthrough 2024 season in which he won seven ATP Challenger titles and reached the final on debut at the Next Gen ATP Finals in Jeddah. At the Australian Open, he eased through qualifying and then overcame Camilo Ugo Carabelli for his first main-draw win at a major. With hype building, the then-19-year-old Tien prepared for a second-round showdown with former World No. 1 Daniil Medvedev.
What came next was one of the more memorable late-night battles in Australian Open history. Competing as the World No. 121, Tien prevailed 6-3, 7-6(4), 6-7(8), 1-6, 7-6(10-7) in a remarkable four-hour, 48-minute clash that ended at 2:54 a.m. in Melbourne. With his win, Tien became the youngest man to defeat a Top-5 opponent at the Australian Open in PIF ATP Rankings history (since 1973).
“I wouldn’t say it turned my career around because I had basically just started, but I think it was a great stepping stone for me,” Tien recalled. “I broke the Top 100 off of that, so I kind of considered it the start of my professional career almost. And it was a big match for me in general. Rankings wise, confidence wise. I’d never made it to the third round of a Slam before either, so it was a lot of boxes checked."
Tien's win against Medvedev was the first of his seven so far against Top-10 opponents. Photo Credit: Paul Crock/AFP via Getty Images
Even after the Medvedev upset, Tien was not done with his breakthrough run in Melbourne. He subsequently overcame Corentin Moutet in straight sets before falling to Lorenzo Sonego in the fourth round. Looking back, the American recognises that fortnight in Melbourne as a milestone both on and off the court.
“I would say after that tournament in general [the off-court side of things] changed,” Tien said. “It was my first tournament in Australia, my first time winning a match at a Slam. So, a big month for me in general.”
Tien celebrates after clinching victory at 2:54 a.m. in Melbourne. Photo Credit: Paul Crock/AFP via Getty Images
Further evidence of Tien’s 2025 Australian Open run as something of a milestone moment lies in the fact that the American has mostly gone from strength to strength since. He broke the Top 50 by August 2025 and the Top 20 in May 2026 after winning his first clay title in Geneva.
Tien nonetheless knows that life on the ATP Tour can be tough and has had his own difficult patches already in his short time as a member of the men’s tennis elite. He appears well equipped to handle the rough among the smooth, however, having established a reputation as one of the most level-headed performers around.
“I think I understand pretty well that tennis fluctuates and that there are ups and downs,” the American said. “You can be on top of the world one week and you can lose first round a couple of days later. I think its just the beauty of tennis, because you can lose first round one week and the next week you can win, too.
“I think I do a pretty good job of handling my perspectives. I know that I’m fortunate to be in the position that I am in, doing what I do.”
Learner Tien's 'Sliding Tour Moment' — Honourable Mention
Starting to work with former World No. 2 Michael Chang in July 2025: “[In terms of] when I started working with my current coach now, after that my ranking has really gone up since then and I think that was a big turning point for me.”
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