's 50th birthday celebration is already one for the books.

The star, who turns 50 on Sunday, got quite the surprise from legendary singer on Friday.

In a clip shared on Instagram, Garner appears to be in awe as she watches a video of Osmond, 64, singing to her for her special day. He suddenly pops up behind her to complete the tune in person.

Garner then stands and hugs him as he presents her with a cake that reads "13 going on 50," a nod to her popular film,

The two go on to sing a duet together before Garner covers her face with a napkin, seemingly still in shock over the moment.

"My first (pre)birthday surprise was a doozy— the one and only, legend in his own time, object of my childhood adoration and devotion— showed up to knock my purple socks off," she captioned the memorable footage.

"He took an hour and a half of his day to sit with me, sing my favorites, and to give me a master class on how to be a class act.

Thank you, Donny. 💜 Hi, . ☺️ I hope to meet you someday, Debbie. ♥️," Garner added to his sister .

Garner first in May 2019 when news anchor shared of performing with The Osmonds wearing brightly-colored jumpsuits, writing, "If this doesn't get you going this morning nothing will.

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