• Via her Instagram Stories, Jennifer Aniston recently shared a throwback photo of Rachel Green and Monica Geller from the 1994 sitcom "Friends" 
  • She shared the photo to celebrate her co-star and friend Courteney Cox's birthday
  • Cox turned 56 on Monday (June 15) and was also greeted by her other "Friends" co-star, Lisa Kudrow

Jennifer Aniston celebrated her friend Courteney Cox’s 56th birthday by posting a nostalgic throwback “Friends” photo on Instagram.

The 51-year-old actress greeted Cox — her “Friends” co-star-turned-longtime friend — a happy birthday on her Instagram Stories with a series of pictures.

"Happy birthday to this amazing human," Aniston captioned a photo that showed Cox smiling.

In her posts, Aniston also apologized for greeting her co-star a day late. The other pictures she uploaded showed both ladies spending time together as well as the 56-year-old celebrant pulling off a silly face.

The throwback photo of the 1994 10-season sitcom came last in Aniston’s slew of pictures. The post was a shot of both actresses on the set of “Friends,” where Aniston played the iconic Rachel Green and Cox starred as Monica Geller.

In the snap, Rachel and Monica are sitting across each other while they paint their nails. The photo also reflects the stars’ close relationship both on- and off-cam.

Meanwhile, another star from the sitcom also didn't forget to celebrate Cox's milestone. Lisa Kudrow — who played Phoebe Buffay in the show — shared photos of her and Cox snuggling together with two dogs.

"Happy birthday @courteneycoxofficial," Kudrow wrote as a caption for Cox’s birthday post. "My genius generous gorgeous grounded great good FRIEND I love you."

Cox turned 56 on Monday (June 15). The birthday celebrant recently made headlines after showing off her perfectly toned body in a black bikini as she cheerfully dives into a pool. The actress posted a hilarious slo-mo video of this, which she shared on Instagram during her birthday.

But Cox’s slim physique wasn't achieved without a lot of hard work. A report by Life & Style in 2019 revealed the 56-year-old actress’ fitness routine to keep herself in shape.

“She’s doing these punishing, no pain, no gain MMA workouts that push her to her absolute limit,” the source said in a statement. “They get her the kind of results she never imagined possible at her age. It’s not even about looking good for roles or for men or anything like that — Courteney is obsessed with being strong and in fighting shape when she’s in her 60s and she’s laying the groundwork for that now.”

"Friends" is one of the most successful sitcoms in American television history
"Friends" is one of the most successful sitcoms in American television history AFP / Angela Weiss