Her first manager, Bob Leone, met the Poker Face singer when at an open mic night in New York 10 year ago, when she was still just Stefani Germanotta.
He told People that the 24-year-old star, famed now for her exhibitionism, was 'painfully shy'.
Leone said, 'She's very different from who she is now. She came to the open mics with her mother twice before she built up the courage to go on stage.
'She was prodigy-like. She was clearly a very good songwriter and keyboard player.'
Leone managed the budding star for six months and in that time watched her transformation from everyday singer to stage icon.
'Going into it, she was Stefani, and she was still writing pop music,' he said. 'By the end of that six-month period, she was officially Lady Gaga.'