MELBOURNE (AGENCE FRANCE-PRESSE, NEW YORK TIMES, REUTERS, BLOOMBERG, GUARDIAN) - He had pretended to be his idol Novak Djokovic as a child, modelling his game on the 12-time Grand Slam champion's as he played matches against his older brother in a parking lot in front of the family's home and elsewhere.
"It was similar like mini-tennis," Chung Hyeon, said. "My model was Novak, and my brother liked Rafa (Nadal) because he is playing also lefty."
All that "practice" being Djokovic paid off last Monday, when the 21-year-old Korean displayed almost superhuman court coverage to prevail against the ailing Serb in the fourth round of the Australian Open.
Chung continued moving through the draw, becoming the first player - man or woman - from South Korea to reach the semi-finals of a Grand Slam, where he eventually fell to Roger Federer. Lee Hyung Taik was the last of the two Koreans to reach the fourth round of a Grand Slam when he made the last 16 at the US Open way back in 2007.
On Monday, Chung will climb to No. 29 from 58th in the rankings; the highest singles ranking ever for any Korean player.
Yet, few could have the forecast such a bright future for Chung, who took up tennis at age six for medical reasons. Struggling with poor eyesight, he would blink constantly and an optometrist who diagnosed him with myopia and astigmatism, suggested he take up tennis.
His mother, Yong Mi, explained through a translator: "The doctor said instead of looking at the tiny letters of the book, it's better to look at the green colour.
"In Korea, all the fences around the tennis courts were green."
Unusually, given the relative obscurity of tennis in South Korea, where tennis lags behind golf and baseball in the popularity stakes due to the small number of courts in its densely populated cities, Chung's father, Seok Jin, had played tennis, as did his older brother, Hong, now 24 and a semi-pro player.
The obvious answer was that Chung would pursue tennis, although he was also a promising taekwondo fighter, and had to make the unpopular decision to do away with the national sport for a much more Western-centric pursuit.
Chung trained at the IMG Academy in Florida for two years from the age of 13 and made the final of the 2013 Wimbledon boys' singles competition. By his 18th birthday, he was ranked in the 60s.
He also completed a month of military training in South Korea, after earning an exemption from the full 21-month stint following his gold-medal win at the 2014 Asian Games in the men's doubles.
He won the 2015 ATP Most Improved Player award and signalled his coming of age by capturing the NextGen ATP Finals in Milan.
"Because of that tournament, he really started to believe, 'I can win tournaments, and I can beat two, three or four good players in a row,'" said Neville Godwin, who replaced Chung's father as coach only a month ago.
While his eyesight remains weak and he still sports spectacles, Chung is now an imposing athlete, standing at 1.88m, one whose acrobatic defence and ability to generate power in extension look very familiar.
Chung's style "reminds me obviously a lot of Novak," Federer added. "The way he's able to slide on forehand and backhand and use the hard court as a clay court and get balls back and stay aggressive in defence."
In 20 years at the top, the 19-time Grand Slam champion has seen plenty of players come and go and he had only praise for the youngster.
"He is already a great player, but we are talking next-level excellence and I think he will achieve that," said Federer, who is into his 30th Grand Slam final as he chases a 20th major title today. "We will see much more of him. Top 10 for sure."
Another former great, Mats Wilander, says Chung's emergence is "very exciting" and the Korean could be the future of the game.
"He is a frightening prospect because I don't think the style of tennis is going in the direction of Roger Federer," the Swedish former world No. 1 said. "It's going in the direction of great athleticism and being aggressive from the back of the court.
"You have to have unbelievable skills to play like Federer and I don't think we'll ever see his style again.
"I think the Djokovic style is the blueprint that Chung has followed and he is reminiscent of Novak at his best.
"But somehow he is more intimidating. He is thicker set and stronger and in terms of playing against him, it must be intimidating. And the scary thing is there's so much room for improvement with a serve that's basically five out of 10."
Practically unknown in South Korea a week ago, Chung - dubbed "The Professor" because of his trademark thick, white-rimmed glasses - has quickly gained superstar status at home. His victory over Djokovic was front-page and home-page news. The mass-circulation Chosun Ilbo newspaper said the world had been "caught by surprise".
Many Koreans were glued to their televisions watching him on Friday, with fan Park Meing Cheon brought to tears in Seoul.
"Unfortunately, with the blister wounds on his toes, I couldn't help crying earlier on," she said.
Yoon Ji Su, from Anyang City, predicted great things from Chung moving forward. "Although the injury is a pity, I hope he recovers well, and I believe there will be great results in the next French Open, Wimbledon, and US Open," he said.
Chung's run drew top television ratings, and media hailed him as "rewriting" the history of tennis in a country which boasts Asia's fourth-largest economy.
"Wow, I watched a tennis match for the first time because it was the talk of the town but I didn't know it was such a fun sport," said one online comment.
For some, Chung's incredible run has also been a welcome break from political issues like a corruption scandal and the conflict among South Koreans about North Korea's participation in next month's Winter Olympics at Pyeongchang.
"I was sick of reading news about on-going politics issues, but now I feel so happy to hear such good news about Chung which is giving us hope," one Korean posted on a news story on the Internet.
With his success Down Under, Chung is already driving sales of tennis products in South Korea. The country's leading online auction and shopping mall website Gmarket has seen a boom in tennis products including shoes, bags, rackets and balls.
Earlier in the week, sales of every tennis-related product rose 24 per cent from a week earlier with tennis shoes seeing the largest increase of 129 per cent.
"It is very rare to see an increase in tennis-related products, as it is winter, meaning it is not the tennis season," Oh Hye Jin, public relations specialist at Gmarket said.
"South Koreans take pride from seeing an underdog South Korean defeating top ranking world players and this is just that," added Roger Park, a sports marketing professor at Hanyang University.
"Tennis" became a trending topic in the nation of 51 million people over the past week and the sport could enjoy the flow-on effect of Chung's success for years to come.
After all, South Korea has a precedent for excelling at a sport after a trailblazer led the way. After Pak Se Ri's LPGA Tour victories from 1998 onwards, South Koreans now dominate women's golf, occupying four of the top six slots in the current rankings. And when figure skating sensation Kim Yuna won gold at the 2010 Vancouver Winter Olympics, it led to a flurry of children lacing up their skates and gliding onto the ice.
Chung's bank account is also set to enjoy a growth spurt. His run to the semi-final has led to talks on a deal with eyewear maker Luxottica Group SpA's Oakley and a surge of interest from companies in using his image to burnish their brands.
Overnight, his Instagram followers exploded to more than 70,000 from about 6,000, said Stuart Duguid, who represents Chung at WME-IMG.
Interest from potential and existing sponsors has been "unprecedented," said Duguid.
Those interests include an endorsement contract with Samsung Securities Co. which will expire soon, opening the door to negotiate a more lucrative deal.
Japan-based Yonex Co. is Chung's racket sponsor and his clothing deal is with Lacoste.
"As a semi-finalist, he is a walking SME," said Chung Min, a research fellow at Hyundai Research Institute, who published a report about the economic effects of winning an Olympic medal, referring to small and medium enterprises.
He estimates that had Chung won the title in Melbourne, it could have been worth around A$10 million (S$10.6 million) for the Korean, including the A$4 million purse and the related boost in endorsements and deals.
Besides being a surprise package, Chung has also endeared fans with his humour on the court, working the crowd with a hand-flapping celebration like many a show-boating National Basketball Association player.
After defeating six-time Melbourne Park winner Djokovic, he wrote in Korean on his social media: "You know this is not the end? Mr Chung will keep moving on!"
After his defeat of Tennys Sandgren in the semi-final on Wednesday, he walked toward the camera and picked up a pen to scribble "Chung on fire!" in Korean on the lens.
South African Kevin Anderson, whom Godwin also coached, said the glimpses of personality shown by Chung in his win over Djokovic are an accurate reflection of the character of the man.
"He's pretty much exactly what he displays. He's a calm guy, with a fantastic sense of humour. He doesn't take himself too seriously - or I should say his position too seriously - he's trying to improve, and win tennis matches, but he's very approachable, a lovely kid."
Chung shyly confided this week that he does not have a girlfriend, and that he likes to eat Chinese food before a match - Korean is too heavy apparently.
And in an interview with a South Korean news agency in November, he revealed his favourite activity: "What I like to do most is just rolling on my bed. I can do that for days."
It is Godwin's job to ensure he does more than that, and he is aware of the challenge if his charge is to make full use of his talents.
"He has got great wheels, but you can't just defend for 10 years as a pro, otherwise you end up like Andy Murray with hip surgery and probably sooner," he said.
He changed Chung's serve in the off-season, bringing his feet closer together to create a more solid platform for him to deploy his extraordinary leg strength.
"It's kind of like an Andy Roddick serve," Godwin said, referring to the retired US star. "Obviously Hyeon's legs are the power base of his game. The more he can bring them into the equation, the better."
Given he has only been at the helm for a month, Godwin adds that he will not be "messing" with things too much - but he has provided some practical advice given Chung's rising star, such as the need to set up training bases in Europe and the US, as well as in Seoul, where Chung likes to return to whenever he can.
In the meantime, Godwin is backing his new pupil to rise to new heights. "The sky is the limit. His progress is really good, he's confident, but quietly confident, and he can go as far as he wants."