*NSYNC reunites at JC Chasez's 40th birthday party

Chris Kirkpatrick, Joey Fatone, Justin Timberlake, JC Chasez and Lance Bass of *NSYNC perform during the 2013 MTV Video Music Awards on Aug. 25, 2013, in Brooklyn, New York.

Rick Diamond/Getty Images

*NSYNC got back together, but only to celebrate a major birthday for one of its members.

All five members of the popular boyband came out in support of bandmate JC Chasez's 40th birthday party Monday night -- and even posed for a group photo.

"JC's 40th... And, if you don't know now you know..." Justin Timberlake posted alongside an Instagram shot of the whole group -- including Chasez, Chris Kirkpatrick, Lance Bass and Joey Fatone.

JC's 40th... And, if you don't know now you know...

A photo posted by Justin Timberlake (@justintimberlake) on

Chasez posted the same image to his own Instagram along with the caption, "So many feels".

If Chasez turning 40 isn't enough to make you feel old, consider this: The group's final album together, "Celebrity," was released 14 years ago.