The blonde actress was thrilled to share a fight scene with the Hollywood legend in new comedy movie 'Serious Moonlight'.
She said: "I got to get in a fistfight with Meg in 'Serious Moonlight'. And she was so game. I was just like, 'Oh, my gosh. I am having a fistfight with Meg Ryan right now. I'm just on cloud nine.' "
Although Kristen enjoyed shooting the action sequence, she admits she found it hard to focus on her role because she is such a big fan of Meg.
The 29-year-old 'Heroes' star explained to Parade.com: "She projects an iconic level of cuteness that I don't even think will ever be matched. She's chosen to take a few years off or whatever, so I forgot how utterly addicting and adorable her mannerisms are. It's like nothing I've ever seen.
"I'm thinking, 'Oh, remember when I first watched 'Joe Versus the Volcano' '. I found it hard to concentrate because she's so cute. You know what I mean?"