Christie Brinkley surprises a sleeping Alexa Ray Joel on her 33rd birthday

Singer Alexa Ray Joel, daughter of supermodel Christie Brinkley and music icon Billy Joel, found herself surprised on her birthday when her fiance and her mother came into her bedroom to greet her — while she was undressed in bed.

"Ok let's get this party started . . . Happy Birthday Sleeping Beauty! #happy Birthday #birthdaysuit" wrote Brinkley, 64, on Saturday. In an accompanying Instagram video, restaurateur Ryan J. Gleason, in a white T-shirt and morning beard, cup of coffee in his hand, enters the bedroom followed by Brinkley, whose hands we see holding a smartphone playing music. At a canopy bed, he parts the translucent white curtains and he and Brinkley begin singing a happy-birthday song to an apparently embarrassed and sleepy Joel, who is lying under white sheets.

Joel, who turned 33, rolls over, exposing her bare back, and mutters, "OK. Thank you." Gleason goes to her side and tells her, "Happy birthday, honey. . . . Here's some coffee."

On Sunday, Brinkley had posted Instagram videos from her daughter’s birthday party at some unspecified warm-weather beach with palm trees. The same day, she uploaded a photo of herself kissing Joel and, confusingly, giving the wrong age, wrote, "What was it? Some 28 years ago . . . you n me kid! I walked into NYHospital and emerged as a proud Mom. You came out singing and made my life a musical! Happy Birthday My precious firstborn!"

Billy Joel and Gleason each separately posted Instagram birthday messages for Alexa Ray Joel.

On Monday, the birthday girl put up an Instagram photo of herself backstage at Madison Square Garden and wrote in rhyme, "What's the best way to turn 33? / Don't take it all too seriously / Live in the moment, yet care where it counts / Love those who surround you to dizzying amounts / And when your spirit gets shattered n' you can't break through / Come to the Garden and serenade this starry city with a rhapsody, or two!"

The choice of locale was unclear. Joel had been a guest performer at her father's Dec. 19 Garden show, but Phish was the scheduled band for Dec. 31.