Rachel from S Club 7 had to stand on a phone book for a photograph with the band's junior counterparts.
S Club Juniors are taller than her - even though they are only between 11 and 14 years old.
Their debut single One Step Closer has just been released.
13-year-old Calvin Goldspink told The Sun: "When I had my picture taken with Rachel, she had to stand on a copy of the Yellow Pages.
"She was wearing high heels, but she was the same size as me."