On January 6, Taeyeon updated her Instagram with a short video that was filmed in a dance studio.
It looked like it was filmed at the studio in the middle of them practicing some dance moves together.
As they stretched them excessively, they were seen getting in pain, then quickly rubbing their thighs where the pain originated.
While watching WINTER and KARINA the whole time, Taeyeon laughed behind the camera.
Over this video, Taeyeon wrote, "Uh-oh, I have a problem. I like these girls too much."
Both Girls' Generation and aespa are at the same management agency SM Entertainment, with aespa being a 13-year-hoobae group to Girls' Generation.
At the end of last month, SM Entertainment announced Taeyeon, WINTER and KARINA to be part of their project girl group GOT the beat.
(Credit= 'taeyeon_ss' Instagram, 'SMTOWNGLOBAL' Twitter)