Sixteen-year-old Juncheng Shang is sitting in the back seat of a car on his way to practice, phone in hand, with the midday Florida sun filtering through the overhead sun roof.

The Beijing-born teen has made time for a quick video interview and exudes a warm, cheery nature throughout our call, grinning from ear to ear under a loud red bucket hat. In tennis-terms at least, it’s wise not to be fooled by his sunny demeanour: the kid is a smiling assassin.

Shang, or Jerry to his English-speaking friends, is the junior world No. 1 but has already made a prolific start to life in men’s tennis, winning his first three singles titles on the ITF World Tennis Tour over the last five weeks and compiling a 16-1 win-loss record at M15 tournaments since the penultimate week in September.

Only Ryan Harrison, a former world No. 40 and also once a fellow junior prodigy, has managed to beat him in that time. It’s safe to say that things are going rather well.

“I think I’m transitioning really quick to the men’s tour,” Shang admits. “This level is obviously really different from the juniors. Some of the guys in juniors play really good tennis, but mentally it’s a lot different. Over here in the pros, tennis-wise, I don’t think they play as good as the top juniors, but mentally they are always there. They will give you a fight in each match.”

So far at least, Shang has often landed the knock-out punch in those men’s scraps, mixing his intelligent court craft and soft touch with excellent movement – traits he has inherited from his parents, who both played elite sport.

“My mum played table tennis which is similar to tennis - you play alone on the court, and she teaches me how to deal with the nerves - and my Dad used to be a football player, so I’ve kind of got the genes,” he says. “My parents are my biggest supporters. I’m just really lucky to be in this family.”

Shang’s talent and determination undoubtedly comes from within, but there is no doubt he has capitalised on the opportunities that have come his way. Few youngsters, for example, have access to their own personal tennis court to hone their craft during their formative years.

“Where my Mum works, they made an indoor clay court just for me playing tennis,” he reveals. “Playing on red clay when I was little was quite cool – it was one of the few courts in China that was red clay.

“Most of the courts in China are hard courts, so playing on red clay gave me many more rallies than I’d have on hard courts. I think that helped a lot since I was little. When I came to Europe I was really confident on red clay, because I’d been playing on it basically my whole life.”

You’d think that might make clay his preferred choice underfoot, but Shang has built a game for all surfaces. Four of his five titles at junior level came on hard courts and he’s improved at each of the junior Grand Slams this year, following his quarter-final finish in the boys’ singles at Roland Garros with a run to the semi-finals at Wimbledon and the final at the US Open, where Spaniard Daniel Rincon pipped him to the title.

Competing at the top of the junior game has given him a glimpse of what to expect in the higher echelons of the sport – should he progress in the way his potential suggests – and Shang believes those experiences have been invaluable in his early development as a player.

“I think that’s the biggest improvement I’ve had so far this year, playing the junior Grand Slams,” he says. “Those big stages are a dream for any tennis player since they are really young. Playing in front of those crowds is really amazing and compared to these [men’s entry-level events], it’s very different.

“They are the biggest tournaments and in those I improved a lot mentally and learnt to control my emotions during the matches. I think that’s the biggest part of my improvement this year.”

Though proud to be the top-ranked junior while still aged just 16, Shang admits he is ready to move on from boys’ competition.

“I don’t want to be stuck here and just be happy about being No. 1,” he says. “Now I’m focussed on becoming a better player and moving on to the men’s.

“Errr, yeh, probably that will be the end (of my junior career).”

It’s easy to see why he’s keen to progress.

Shang, who travels with his father and doesn’t have a permanent coach, trains at the IMG Academy in Bradenton - an environment that regularly hosts ATP and WTA stars and brings a close connection and clearly trodden path to the top of the sport. Making the move over there from Beijing might have taken a little bit of adjustment at the time, but he’s thriving now.

“Moving away from home when I was 11 was kind of difficult for me, but I think I’m the kind of kid that gets used to other places, you know,” admits Shang. “I really enjoyed the first time I came to Florida. Having those practices with players that you’ve never played in your life and having those coaches around me is really special.

“I’m pretty good friends with Denis Shapovalov,” he continues. “Whenever he comes to IMG we always hit together and hang out. Sebastian Korda as well – we live really close by, so I also ask him to play golf… I’m a big fan of golf!”

Despite the company he keeps, Shang is clearly keeping both feet on the ground even with the background hum of excitement around his potential.

China, whose brightest tennis export came in the form of former world No. 2 and two-time Grand Slam champion Li Na, has never seen a male player reach the top 100 in singles.

Could Juncheng Shang be the next big thing?

“I’m in the early stage of my career so I think it’s important to build one step at a time and not think about the big dreams,” he says, cautiously.

“Obviously being Top 100 – and becoming the first (Chinese man to do so) – is a big dream for me, but it’s more important to keep building in practice and in matches.”