As this year's Australian Open approaches its finale with only a handful of players left, there is also only a handful of racquet stringers left, and Kui Zhang is one of them.

Key points: Tennis racquet stringing requires precision and speed

Tennis racquet stringing requires precision and speed There are only a few dozen stringers qualified enough to work at grand slam tournaments

There are only a few dozen stringers qualified enough to work at grand slam tournaments More than 500 racquets are strung at the Australian Open on the busiest days

Traveling from China as part of the official stringing team, Mr Zhang is working around the clock at his second Australian Open.

"I start from 8:00am and finish around 8:00pm or even later. It's very tiring but satisfying once the work is done," Mr Zhang told the ABC.

"After my flight arrived in Australia, I checked into my hotel and then started working straight away. I didn't have time for sightseeing, it's all work."

His teacher, former Australian Open stringer Sam Chan, was among the audience this year watching over his favourite players on the court.

Over the past two decades, Mr Chan has worked at 17 grand slam tournaments, including all four of the majors, looking after the racquets of the world's top players, such as Roger Federer, Rafael Nadal and Serena Williams.

Only a few dozen qualified to string at grand slams

Sam Chan strung for Serena Williams at Wimbledon in 2002. ( Supplied: Sam Chan )

In the late 1970s, Mr Chan quit his job as a fashion designer in London to become a professional stringer traveling to tournaments alongside his wife Corrie who speaks six languages and was working in administration in the stringing room.

The now 69-year-old said there were only a "handful" of people qualified to string at grand slam tournaments.

"There are about 30 to 50 people in the world at that level, but usually it's about 20 people who always go around the world stringing," he told the ABC.

"You've got to be fast and accurate. You have to be good in both ways, but getting to a certain level is very difficult."

Mr Chan said at a grand slam level stringers were expected to string a racquet within 15 to 18 minutes, while if it was a racquet for a player currently on court it needed to be done in about 12 minutes.

Racquet stringing is the craft of actually pulling the string through holes on a racquet to a certain tension with the help of a machine.

It's crucial for players who are hitting shots with centimetre precision — too loose or too tight and balls will go flying or fall short.

'You've got to know someone to get in'

Sam Chan says a stringer has to be "fast and accurate" to work at grand slams. ( Supplied: Sam Chan )

At this year's Australian Open, up to 500 tennis racquets go through the stringing room every day.

But being one of those selected to work with the tools of the world's best players is no easy feat.

"It's not an open environment for people to apply to string [at a grand slam]," Mr Chan said.

"You've got to know someone who can introduce you or someone who thinks you're good enough to be invited — it's a very closed business."

Mr Chan said stringers usually received a small stipend for their work, but sometimes didn't get paid at all.

"One thing a lot of people don't realise is that in this business they don't get much pay," he said.

"If you string at home or in a shop, your wages are better off than stringing at tournaments, it's very low pay."

Mr Chan said at most grand slams stringers received about $US200 ($300) a day as well as hotel and airfare cover, were often expected to work more than 12 hours a day and sometimes had to skip meal breaks.

'When you die off, someone else can step in'

Melbourne stringer Kuankuan Wang with Sam Chan and his wife Corrie at the Australian Open. ( Supplied: Kuankuan Wang )

Mr Chan is now retired and living in Melbourne, but he is hoping to bring more new blood into the business through teaching.

"When you die off, someone else can step in," he said.

"Tennis business is dying down a bit … but we still have a lot more tennis clubs compared to other countries and lots of tournaments for the juniors compared to England; in England they don't have enough facilities compared to here."

Despite the low pay and intense work, many local tennis lovers are still trying to crack into the grand slam stringing business.

Kuankuan Wang is one of the few up-and-coming Chinese stringers in Melbourne. He teaches at a university by day and strings at his tennis shop by night.

Stringing tennis racquets is quite the art form. ( ABC News: Kai Feng )

His love affair with tennis began a decade ago, which led him to move and settle in the Australian tennis capital.

"When I first came across tennis I was studying at Xiamen University. Tennis was one of the elective subjects, and I have loved it ever since," he told the ABC.

"I immigrated to Melbourne for the Australian Open. I pursued it all the way here from China, I came to study, then immigrate and now I have settled down and have my own career."

Although Mr Wang is relatively new in the business, he's already eyeing off the grand slams.

"The main drive comes from the love of tennis. It is difficult to keep it going for a long time if you're only here for money," he said.

"I'm kind of new compared to other stringers as this is my second year of stringing, but my ultimate goal is to string at all four grand slams."