Gary Glitter was in his stage costume of a silver sequinned jumpsuit when he slid his hand up a 13-year-old girl's skirt and told her it was their "secret", a court heard.
The glam rock star's alleged third victim idolised the singer, and said she was molested after she went to see him perform in Watford, Hertfordshire.
Giving evidence, the 48-year-old woman tearfully recalled seeing Glitter at Baileys nightclub. She was introduced to him by her mother's partner.
The woman told London's Southwark Crown Court: "Gary Glitter was my idol, and he (mother's partner) said that he would arrange for me to go there and see him in concert, and meet him afterwards."
The jury heard that, together with her mother and her partner, the young girl was invited into the dressing room where Glitter was sitting with his bodyguard.
The court was told that, after a while, Glitter asked if the girl could be left alone with him, and that his bodyguard, her mother and her mother's partner left. Glitter kissed the girl, before sliding his hand up her skirt and indecently assaulting her, jurors heard.
The alleged incident is said to have taken place between October 1979 and December 1989, and Glitter (70) - real name Paul Gadd - is accused of two counts of indecent assault.