Tuesday marked Jennifer Aniston’s 51st birthday, and the “Morning Show” star received a sweet birthday shoutout from her longtime friend and former “Friends” co-star Courteney Cox.

“No matter how hard you might try… there’s only one Jennifer Aniston,” wrote Cox in the caption to a selfie of the pair, who are wearing matching glasses, black tops and similar hairstyles.

RELATED: Will Ferrell Answers Jennifer Aniston’s ‘Burning Questions’ As She Guest Hosts ‘Ellen’

“Happy birthday my dear friend @jenniferaniston!” she added. “I love you!”

Cox, 55, isn’t the only celebrity pal sending birthday wishes to Aniston. In fact, her current co-star on “The Morning Show”, Reese Witherspoon, likewise sent a message via Instagram.

RELATED: Selena Gomez Fangirls Over ‘Ellen’ Guest Host Jennifer Aniston, Recalls The First Time They Met

“Happy Birthday Jen!” writes Witherspoon. “I couldn’t ask for a better friend and partner to chase my dreams with. Life is way more fun with you in it!!!”

Also celebrating is Aniston’s longtime makeup artist Angela Levin, who took to Instagram to share a photo of herself giving Aniston an touchup.

“Happy birthday my darling, my love, my golden sunshine, so many years we are together and you still take my breath away,” she wrote in the caption.

Meanwhile, Ellen DeGeneres sent out a birthday tweet.

Even Aniston’s ex-husband Justin Theroux sent along a birthday greeting, taking to Instagram Stories to share a fierce photo.

Justin Theroux/Instagram
Justin Theroux/Instagram
Click to View Gallery
Jennifer Aniston’s Top Roles