The tennis world learned a lesson at Australian Open 2026.
Learner Tien is the real deal.
The 20-year-old American arrived at Melbourne Park seeded at a major for the first time, a year after reaching the fourth round as a qualifier.
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His progression was unmistakable.
Over the past 12 months, Tien has added significant weight to his game: his average first-serve speed climbed from 175km/h to 185km/h, he generated three per cent more winners from both wings, and he finished AO 2026 having used the drop shot 17 more times than at the same event last year.
The creativity in Tien’s arsenal was so pronounced that third seed Alexander Zverev, after edging him in four sets on Tuesday, offered praise.
“I don't think I've played someone with this level from the baseline since a very long time,” Zverev said.
“I don’t know what [coach] Michael Chang has done with him in the off-season, but the way he’s playing is incredible. I probably would not have won today without my 20 aces.”
MORE: AO 2026 men's singles draw
Tien will rue his nine double faults, but an 11-point edge in rallies lasting five shots or more underscored how far his baseline game has evolved.
“Obviously, I know I've been playing great tennis. I know maybe even coming to this year in Brisbane, maybe I wasn't playing amazing, and even starting off my tournament here, I wasn't playing incredible by any means,” Tien said.
“But I think very happy with how I was kind of improving with each match. I think, you know, match by match, day by day, I just felt a little bit more comfortable.
“I felt like I was seeing the ball a little bit better. By the end of the tournament, I was playing very well. I'm very happy about that.”
Another promising sign was the sea of yellow L-plate signs scattered throughout the stands. Back-to-back second-week runs at Melbourne Park have turned Tien into a crowd favourite, but he and his team are careful not to let momentum become a distraction.
“I don't think about it too much. I don't feel like a weight on my shoulder by any means,” he said of the rising expectations that accompany deep Grand Slam runs.
Asked what must improve to sustain an elite level across a full season, Tien pointed to his serve, physical strength and speed.
“I think my serve can improve … physically, I wouldn't say I'm close to where I hope to be one day either, but I think weeks like this are good to test myself.
“I get a lot of takeaways from winning and losing these matches. It's great. It just really sets me up to come back and be even better the next time I play.”
Tien’s trajectory was already steep before AO 2026.
In 2025, he recorded top-10 wins over Zverev, Andrey Rublev, Ben Shelton and Daniil Medvedev twice, and the appointment of Chang in July proved a catalyst for his next phase of growth.
The youngest men’s singles Grand Slam champion in history, Chang also guided former world No.4 Kei Nishikori to the pointy end of the world rankings, establishing a reputation for refining young talent at the highest level.
“He's always a very calming presence,” Tien said of Chang.
“He offers me a lot of stuff mid-match, especially stuff that maybe I'm not picking up on. You know, a lot of it was encouragement, telling me to stick with him as best as I could.”
Tien won 36 of his 60 matches in 2025, claimed a maiden ATP title in Metz, and captured the Next Gen ATP Finals.
He leaves Melbourne as the youngest men’s Australian Open quarterfinalist since Nick Kyrgios in 2015, and the youngest American to reach a maiden Grand Slam quarterfinal since Andy Roddick at the 2001 US Open.
He also joins Roddick, Frances Tiafoe and Ben Shelton as just the fourth American man since 2000 to reach a Grand Slam quarterfinal before turning 21.
And if that wasn’t enough, he’s the only man to win a Grand Slam set 6-0 over three-time AO finalist Daniil Medvedev.
Now, having won 14 of his past 18 matches, Tien leaves Melbourne on a high as the tour shifts to the American hard courts.
“The fact that I was able to make it to the quarters, that was a goal of mine coming into the year,” he said.
“So happy to check that box in the first Slam of the year.”