Alex Rodriguez's daughter asked Jennifer Lopez for her dress the first time they met.

The 'On the Floor' hitmaker reminisced about coming face-to-face with her soon-to-be stepdaughter Ella for the first time as she shared a touching birthday message to the youngster when she turned 12 on Tuesday (21.04.20).

Jennifer shared a photo of her and Ella embracing on Instagram and wrote: ''To my loving little Ella ... the first day I met you (you were so little then...), you ran up to me, sat right on my lap, put your arms around me and asked to have my lavender dress I had just worn to the Grammys for when you grew up.

''You won my heart in a split second ... you're not so little anymore but you're still sitting on my lap and I love it!!! (heart emojis) HAPPY BIRTHDAY sweet girl! #ThisPicIsUs (sic)''

The 50-year-old star ended her message by reassuring Ella the Ralph & Russo gown - which featured a deep cutout, small train, thigh split and ruffle detail - will be hers one day.

She added: ''PS: I have the dress saved for you!! [flower emoji] (sic)''

Alex - who, as well as Ella, also has 15-year-old Natasha with ex-wife Cynthia Scurtis - paid his own tribute to his daughter and spoke of how ''proud'' he is to be her parent and praised her dedication to her school work.

He wrote on Instagram: ''I can't say enough about how proud I am to be your dad, Ella. You are growing up so fast. You are mature, and wildly talented. You can sing and act and I know you loooove to dance.

''What I'm most proud of this year is the dedication you have given to your studies. You really improved your grades this year and that means so much to me. Making a commitment to education yields so many rewards later in life.

''And I can't wait to see what life brings you. Happy 12th birthday #EllaBella!! I love you so much.(sic)''

Jennifer - who has 12-year-old twins Max and Emme with ex-husband Marc Anthony - previously admitted both the retired baseball star's kids and her own daughters often ask for her old red carpet gowns.

She said: ''Ella told me, 'I want your dress with the orchid and Emme is like 'What about that [dress], Mommy? Are we gonna keep that? Don't throw that out. They tell me all the time.''