Learner Tien got his name because his mum was a teacher and the rising star of United States tennis still lives at home even as he reached a Grand Slam milestone.
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The 20-year-old talent will be the youngest men's singles quarterfinalist at the Australian Open since 2015 when he faces Alexander Zverev in Melbourne.
Tien's mother Huyen, a retired teacher, and the rest of the family have played a central part in his fast rise to prominence.
"I do still live at home," the unassuming Tien, whose parents emigrated from Vietnam to the United States, said on Sunday after thrashing three-time finalist Daniil Medvedev in straight sets at Melbourne Park.
"I think sometime this year I'll probably get my own place," added Tien, who has already racked up prizemoney of more than $3 million in his young career.
Tien was born in California and is now coached by Michael Chang, who famously won the French Open as a 17-year-old in 1989.
His father, Khuong, coached him when he was a small child and Tien's sister is called Justice – because Khuong is a lawyer.
The family remain very close-knit despite Tien's ascent, which includes a first ATP title in November.
In December he won the Next Gen ATP Finals for rising stars of men's tennis.
He only turned 20 last month and the left-hander said: "My parents are still very much involved in my life and I'm very grateful to them for it.
"My family has been such a big part of my life forever, and it's hard to think of a life without them.
"So I'm very fortunate. You know, they still do a lot for me."
Tien suffered a nosebleed early on against Medvedev in their last-16 match, the result he said of a dry nose.
But after that he made surprisingly easy work of the former world No 1.
Ranked 29 to Zverev's three, the German will be clear favourite when they meet on Tuesday.
But Tien struck a quietly confident tone.
"I feel like I have been playing a little bit better match by match, and, you know, each match I'm making a little jump in how well I'm playing, how comfortable I feel," he said.
"Right now I'm feeling better than I have all week, all year, so I'm really looking forward to it."