The 27-year-old asked on Twitter while watching One Direction's MTV VMAs victories whether it is "legally okay" for her to have a crush on teenage members Harry Styles and Zayn Malik.
"Aw just watching One Direction perform at this years VMA's!" she wrote. "Their really taking over the US! I'm so happy 4them. Stalked them on xfactor lol.
"Ps: Is it legally ok for me to perv on Zane yet? Or Harry? I'm not fussed. Who ever hits 18 first really."
Buchanan later revealed that she wasn't the only person having amorous thoughts about a celebrity singer, tweeting: "Oh my daze...My mum just told me that she had a dream that her & Usher went on a date!!
"Shall I throw up now or l8r?"
Buchanan recently reunited with her original Sugababes bandmates Mutya Buena and Siobhan Donaghy. The trio have promised to release new music by the end of 2012.
Photo galley - MTV VMAs ceremony: