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Brie Larson Was In '13 Going On 30,' So She Goes *Way* Back With Mark Ruffalo

It feels like it's difficult to talk about any movie other than Avengers: Endgame right now. The climactic final chapter of the Avengers movies opens in theaters everywhere on April 26, and it just had its premiere in Los Angeles Monday night. Avengers: Endgame is the main movie news at the moment, so it'd be easy to not even notice that 13 Going On 30 just celebrated its 15th anniversary. Luckily, there's a surprise connection between Avengers and 13 Going On 30 that both fans and the movie's stars are flipping out over. It turns out that Brie Larson was in 13 Going on 30 so she and Mark Ruffalo go much farther back than their Marvel movies.

13 Going On 30 premiered in movie theaters back in 2004 and starred Ruffalo as the grown-up version of Jennifer Garner's character Jenna's childhood best friend. But before the movie jumps ahead to the characters lives in their 30s, the audience meets Jenna and her friends as 13-year-olds. It's during those scenes, set in the 1980s, that audiences see Jenna interact with a group of mean girls known as "The Six Chicks." Larson was a Six Chick herself, and Ruffalo was stunned to learn that fact for the first time at the Avengers: Endgame premiere. He and Larson currently both star in Avengers: Endgame, but he was surprised to find out it wasn't the first time they had worked on the same project. Entertainment Tonight brought the nostalgic fun fact to Ruffalo's attention. You can watch the moment he finds out that he shared a screen with Larson over a decade ago in the clip below:

In the red carpet clip, Ruffalo and his wife Sunrise Coigney look at a still image of Larson decked out in 1980s garb in a scene from 13 Going on 30. Ruffalo says that the girl in the picture looks just like Larson, while Coigney very astutely points out that it makes sense that the girl in the photo and Larson look alike since they are the same person. You can see Larson all the way to the right in the photo below:

Columbia Pictures

When Ruffalo realized that he and Larson go way back, he had just about as big a reaction as any fan would. With a big laugh, he said, “She was a mean girl! Oh my god. That’s amazing. Wow, I didn’t know that. How come I didn’t know that?”

ET also spoke to Larson about her role as a Six Chick while she was on the Avengers: Endgame red carpet. She said that filming 13 Going On 30 when she was 14 years old was the moment she knew that some day she wanted to direct. That dream came true, since fans can now watch Larson's directorial debut on Netflix. She directed and stars in the comedy-drama Unicorn Store, which is streaming now.

While 13 Going On 30 came out 15 years ago, you can watch Avengers: Endgame when it hits theaters on April 26.