Zheng Wushuang, China's No 2 junior player, occupies 18th place in the world junior rankings. Chen Xiaowei / Xinhua

Game, set and match?

The girls' achievements have repaid Yi's five years of belief and commitment. Zheng has reached several finals on the ITF Junior Circuit and now sits in the top 20 of the world junior rankings. In July, Cao Siqi, 16, won the 2015 Agile Cup International Tennis Federation Junior Circuit in Beijing, and having just started her professional career, Wang Yafan, 21, has climbed to 126 in the World Tennis Association's rankings.

"Competing overseas has opened my eyes. I can learn a lot from my opponents from other countries, which encourages me to do better and better," said Cao, whose highest ITF ranking last year was 58, before an injury saw her slide in the pecking order.

"My goal is to play the Grand Slam like Li Na, and win it," she said.

Coach Zeng also has high expectations of his young charges. "The players here are high quality and I'm very confident about them," he said. "Although it's difficult to say how long it will take, their performances have already been beyond expectations, and I'm looking forward to bringing up the next Li Na."

For her part, Yi is determined to temper ambition with patience. "My ultimate goal is to see another successful player like Li Na, but I'm not going to rush things. I'll accompany the players to ensure they progress and grow gradually and normally," she said.

"Our original plan was to see the current level of achievement after about eight years, but we got there in just five years. It's kind of like burning money, but I love tennis and I'm confident that all the players have bright futures."

leilei@chinadaily.com.cn