f(x)'s Sulli updated her Me2day with a new photo on 19th January.
She wrote,"Sohyun Suzy Jiyoung Sul. Jiyoung ah Happy Birthday. Congratulations for turning 20, you know my heart even if i don't say right?"
The girls are seen posing happily with the birthday cake.
Fans commented,"i see heaven","Jiyoung is such a lucky girl","jealous" and etc.