Donny Osmond surprises Jennifer Garner for her 50th birthday

Jennifer Garner got the best surprise for her 50th birthday: Donny Osmond.

Garner took to Instagram over the weekend to gush about meeting Osmond, 64, and share a glimpse into their time together.

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

"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," Garner continued. "Thank you, Donny."

The video starts with Garner watching a musical video message on her phone featuring Osmond, who then sneaks up behind her with a cake which reads "13 Going on 50." The look on the "Alias" alum's face as she realizes what is happening is priceless.

The duo even crooned "Make the World Go Away," a song that was originally recorded by Ray Price but was later a hit for Osmond and his sister, Marie Osmond.

"I seriously think this is the best surprise that could ever be! The joy!!!!" Rita Wilson wrote in the comments, alongside the many celebrities sending Garner best wishes for her birthday.

In his own Instagram post, Osmond wrote that he was "overjoyed" to surprise Garner for her special day and he invited her to perform with him in Las Vegas, where he has a residency at Harrah's.