- Sun Zheng is the first F3 racer from mainland China to enter the Macau Grand Prix
- He aims to graduate to F1 racing to become first Chinese to compete internationally
- Macau Grand Prix regarded as one of the toughest training grounds for future F1 drivers
- The Galaxy Double R Racing Team holds the Macau speed record of 182 mph (292 kmh)
Amid the whine of F3 engines and the clatter of pneumatic tools, 21-year-old Sun Zheng -- one of mainland China's small but growing pack of motor racing drivers -- considers his form for the next day's racing at the Macau Grand Prix.
"My time wasn't very good and there were three corners we kept missing," he tells CNN from the relative calm of the Galaxy Double R Racing Team's catering tent. "If I solve those three corners, I'll be two seconds off the pace."
As the first F3 racer from mainland China to enter the Macau fixture - roundly regarded as the sport's toughest training ground for Formula One drivers -- Zheng has a lot resting on his young shoulders.
"Of course, all F3 drivers want to be F1 drivers and Macau is like doing college," he says, adding that his ambition is to become China's first F1 driver at a Federation Internationale de l'Automobile (FIA)-sanctioned event.
"Most older drivers have done three or four years and then they graduate to F1. I hope I'll be first. I have driven in Formula Ones and nothing can compare with it -- it's in a different category," he says.
As the reigning China Formula Grand Prix series champion, fourth place-getter in the final 2012 Audi R8 LMS Cup and this year's national champion in the British F3, Zheng has already shown the kind of form that could take him to the pinnacle of motor racing.
At the moment, however, he needs all his concentration for Macau which he says is one of the most challenging circuits in the world. Even at the tender age of 21, he says the rigors of the track leave him exhausted at the end of the day's racing.
"Physically I'm okay but mentally I'm very tired because you're not just driving the car - it's not like qualifying or practice -- when you race you have to try to overtake, you have to try to defend, you need to think about a lot of things in a very short space of time.
"When you take risks, it's not like you can just do that blindly," he says. "You have to think, 'Okay well ... I have a 60-70% chance I'm going to go for it.'"
As a street circuit, the concrete canyons of Macau's Guia Circuit can throw up some chilling moments, even for experienced drivers who take some corners at upwards of 240 kph (150 mph) on each lap.
"You have to really push every corner and every lap during the race because the older drivers, the pace that they keep up is incredible," Zheng says. "They are preparing for Formula One races so they can't make mistakes -- they're not just fast on one lap, they're fast on every corner and every lap.
"I have done endurance races where you have a lot of time to take a rest; you're not competing with the car next to you. But in F3, once you start, it's a fight to the end.
"When I start, I take a breath when the right light goes off and I push and push until the checkered flag comes down and then I let that breath out -- it really does feel like that."
With 15 laps at around two minutes a lap, 30 minutes might seem like a long time to hold your breath but, as Zheng explains, Macau is that kind of circuit.
"On other tracks, there's a white line on both sides of the circuit -- if you take a short cut and your four wheels go over the white line, then that's a penalty," he says. "But in Macau, the white line is a wall -- not even two wheels can go over; it's really difficult."
Double R Racing team manager Anthony Hieatt says his team has had some hair-raising moments at the Macau Grand Prix in the past.
"Crashes? Oh God yeah. Massive crashes. Huge ones," says Hieatt amid the drone of the F3 garage. "This is the toughest circuit in the world bar none -- it's probably one of the longest circuits with 23 or 24 corners and parts of it are like putting cotton through a needle.
The good drivers, he says, will always stand out.
"Good experienced drivers are always up the front and new drivers are always at the back. New drivers need experience so they come back two or three times but if you do succeed at Macau, then all the Formula One people are watching -- it's a calling card for your career."
His team currently holds the record for the highest speed ever attained at Macau at 182 mph (292 kph) which through the narrow historic streets of the former Portuguese colony is about as fast as it gets.
"To put it in perspective, they don't reach those sorts of speeds at Monaco," says Hieatt, adding that intense concentration is fundamental to every driver's survival at Macau.
"As soon as the driver feels they're safe, they're in the morgue," he says.
While advances in the carbon fiber monocoque design have made the racers safer than they were 20, and even 10 years ago (F3 racers now fitted with thick panels that protect drivers from intrusions into the cockpit), the last thing a driver wants is 'to go in', says Hieatt using the pit vernacular for having a crash.
"It's still a dangerous sport and it still hurts when you go in, but the cars are among the safest in the world."
For Hieatt, F3 -- as the poor man's Formula One -- represents the real, gritty spirit of motor racing in its purest form.
"Here we're dealing with raw talent," he says. "The F1 drivers always remember F3 because there's this fantastic bonding that goes on because they work with a small team.
"In Formula One, the mechanics wouldn't even speak with the drivers, but here they eat, drink and sleep with the team. It's really the university of racing."