After the last note, Lee threw his hands in the air, like a gymnast after a golden Olympic performance. The audience of 100 erupted in a standing ovation.

Lee was invited onto the weekday programme - which has earned 35 Daytime Emmy Awards during its eight seasons - after his YouTube video won almost two million views since going viral in September.

Lee began playing piano aged three, has already climbed to grade five standard and cites Mozart as his favourite composer - and perhaps role model. He told Ellen: "He plays well and he is a music prodigy."

Showing his age, Andy added he chose a white outfit to meet America because it is prettier and said he would like pet dogs named Teddy and "little flower".

Music teachers say it usually takes a pupil four to five years to reach grade five, while an outstanding student may accelerate to this level in two or three years.

Wilson Chu, consultant of the Vienna Music Examination Board, who has seen local children learning instruments at age two due to parental pressure, warned against hot-housing, saying students cannot learn effectively before the age of four.

"Putting too much pressure on them could backfire," he said, adding that it is better for children to play an instrument for a few years before sitting exams.

The London-based Associated Board of the Royal Schools of Music sees about 310,000 non-British candidates every year.

Hongkongers make up one third of them.