"This trip was inspirational and beneficial," said Chung. "It is the first step for me to become an outstanding football player."

Watch: How soccer and a chance to play at Bayern Munich changed a rebellious teenager

Chung won the trip after being judged the most valuable player at the Allianz Junior Football Cup in Hong Kong in July. Besides training, she met Bayern stars including German World Cup winners Manuel Neuer and Bastian Schweinsteiger, and also watched the season opener against Wolfsburg.

"I was very happy to take photos and get autographs from the stars. I also saw how good the youth players of other countries were. They are very aggressive and the boys didn't slow down to avoid body contact on the pitch. Therefore I also need to be more physical," Chung said.

"I learnt to communicate with the other players, and if we couldn't do so with our languages, football was the medium for us," she added. "I really want to pursue a career in Germany, or elsewhere in the world."

But wherever her soccer career takes her, Chung's mother So Po-chu will never be far from her thoughts. So endured plenty of parental angst as her daughter fell in with the wrong crowd.

"I ignored her and didn't listen to her. She was always angry and worried when I came home late, or didn't get home till dawn," Chung said. "I was naughty and disobedient, and I scolded her with bad words. I'm sorry."

As Chung starts to tear up, her mother comforts her and maintains she was good and smart, finishing her homework on her own. Despite being a disabled single mother, So said raising Chung was no hardship.

Chung said her football career was nearly derailed because of her rebellious ways but she returned to the game because of her love for her family.

"Some of my friends … saw I used sign language to communicate with my mum and laughed at her. I was upset, but determined to protect my mum by showing I was strong," she said.

Instead of hanging out in the neighbourhood, she now spends most of her spare time training. As a right-sided midfielder or full back she represented Hong Kong at the under-16 level and is now a member of the under-19 team.

Now, the boys who laughed at her and her family no longer bother her; they were impressed by her achievements.

"I always think of my family when playing, and I will continue to fight for them," she said. "Mum has been a great support. She didn't follow my matches, but always backs me. She cooks meals for me, and boils herbal tea when I have a sore throat."

Chung Siu-hin, one of Vicky's two older brothers, said her mother faced big challenges.

"Our parents separated many years ago. It was tough for my mum to raise three children. I was the one who went out to find Vicky and bring her home after midnight, but actually I wasn't a good kid either," said the 17-year-old, who left school after Form Three as he "didn't want to study any more".

"I had some discussions with her after the trip. I can tell her mindset has changed and she is more mature than before," said Siu-hin, who said his sister's efforts had inspired him.

"Last year I went back to school and I will take the [Diploma of Secondary Education] exams next year. Thanks to Vicky's achievement, I'm encouraged to do better. So besides my studies, I also do self-study in English to be better equipped."

Vicky also thanked Siu-hin. "He is my role model. In the old days he was always worried about me when I played on the street … and kept phoning me.

"He always cares about me. And then he started to work to provide financial support to the family … I really couldn't go on in sport without his sacrifices."