After recording the song in his shirt emblazoned with Vietnam's national flag, Ninh Duc Hoang Long uploaded it on YouTube. He woke up in the morning amazed that his effort had attracted heaps of viewers.
Several days later, television and newspaper reporters contacted him for interviews. Long's popularity spread even further when they described him as a newly discovered internet star.
Long was born in 1991 in the northern province of Ninh Binh. No one in his family had pursued a musical career, but he dreamed of being an opera singer since when he was young. Once he had a chance to enjoy a performance by Luciano Pavarotti (1935-2007), the Italian tenor. He immediately decided to study opera like his idol.
After two years studying at the Vietnam National Conservatory of Music, last year Long received a scholarship to study music in Hungary. He was the only foreign student who passed the entrance exam to study opera at the Franz Liszt Academy of Music in Budapest.
Long's teachers suggested Long sing at a university meeting. He decided to perform Hazam Hazam (My Country), an extract from a opera titled Bank Ban. "This is a very familiar patriotic song in Hungary," Long said. "All Hungarians know it."
Despite its popularity, not many can sing it well, because it requires operatic techniques.
"Many Hungarian journalists and YouTube users told me that singers, including foreigners, had performed the song, but only two had the power to move people - one is an Hungarian singer, the other is myself," Long said.
Long spent two months practicing the song to prepare for the entrance exam to his university. It made him proud when the jury applauded his performance - the only one to be so honoured.
That's the reason why he was confident enough to perform the song once again in front of friends and teachers.
One leading Hungarian e-newspaper, index.hu, praised Long as "a newly discovered star on internet, a Vietnamese boy singing Hazam Hazam so well it makes your flesh tingle," he wrote.
A reader of newspaper, Zsanett Zsefy, said Long had a fantastic, beautiful and brilliant voice. "He performs the song with ease and moves the audience," he said.
Suddenly becoming famous, Long firstly felt surprised. Now he's so happy and proud that he helps people know more about Vietnam.
"Now everyone knows Vietnam's national colours," he said. "And the name of the country is in most Hungarian newspapers. Many people told me that they now want to travel to Vietnam some day."
Although the song is about Hungary and its people's patriotism, Long always thinks of Vietnam and his homeland while singing.
"Living far from home, I often feel nostalgic," he said. "Recently, I listened to the news of China's intrusion into Vietnam's sea territory and became indignant.
"I send my love and nostalgia for my country through the song. Probably, that's the reason why I can touch an audience's hearts."