A program training ball boys and girls leads some to work in major international tennis competitions. Li Yingxue reports.

They were training to compete with tennis balls-but not to play tennis, per se.

Instead, the 20 kids were participating in the Beijing region's training and selection camp for ball boys, the best of whom will go on to work at the 2018 China Open.

Guo Shanqing has returned after failing to make the cut last year.

The 12-year-old, who has played tennis since age 6, was determined to pass after training for about an hour-and-a-half every day during the past year.

He's among 11 finalists from the Beijing region selected from among 200 participants aged 9 to 16.

Guo will attend the summer camp to further train in July to compete for a spot at the China Open in October.

"I've watched the China Open in person many times," he says.

"The players are so fierce. I have a long way to go to become a professional player like them."

This is the seventh year of the selection program and the second year of the training camps.

The program director Han Mengwei says more games have been added to teach participants more about tennis.

"We only did interviews and tests last year," she says.

"This time, we first ensured they enjoy tennis. Then, we selected candidates suitable for our program."

This year's selection extends to 10 cities, including Shanghai, Guangzhou and Shenzhen. Each city will shortlist 280 children and then pick the top 5 percent to attend summer camps.

"We're looking for kids who serve others and stay focused," Han says.

"The job is both dynamic and static. It's a process of learning to serve players without talking. And each working session lasts 45 minutes."

Han took six youngsters from the 2017 China Open to work at the Australia Open in January.

Some 180 will be selected to serve at this year's China Open. Six will get the chance to work at the 2019 Australia Open, and four can serve at the French Open next year.

"Those who've gone to Australia took care of themselves and made many friends from other countries," Han says.

"The China Open connects all of them. It provides them a community of friends and tennis."