Courteney Cox has paid tribute to Jennifer Aniston on her 55th birthday.

The actress took to Instagram on Sunday evening to share a sweet post celebrating her Friends co-star's 55th birthday.

"Happy Birthday my sweet Jenny Louise," Courteney, 59, wrote in the post, "Also don't know why I call her that...but I sure do love you."

In the post, the Cougar Town actress shared two photos of herself and the Just Go With It star.

Courteney also shared a clip of a scene from Friends in which Jennifer's character, Rachel, talks to her late co-star Matthew Perry, who played Chandler Bing in the 1990s sitcom.

"Hey Chandler, Monica (Courteney) just broke my seashell lamp," the actress said in the clip.

"Not sure why this is one of my favorite clips...," Courteney wrote in the caption. "I guess it's because nobody else in the world could make this line sound so cute."

In response to the clip, Jennifer joked in the comments section of the post, "You BROKE IT! I love you."

The duo starred in Friends from 1994 to 2004 alongside Lisa Kudrow, David Schwimmer, Matt LeBlanc and Matthew, who passed away in October last year.