‘Guardians of the Galaxy’ Cast Takes on a 5-Year-Old Marvel Expert on Kimmel (Video)

Fun fact: Vin Diesel met co-star Bradley Cooper for the first time backstage

The “Guardians of the Galaxy” cast either doesn't know much about the comic book property they just created for the big screen, or love letting little girls win.

Chris Pratt, Zoe Saldana, Bradley Cooper, Vin Diesel and Dave Bautista faced off against 5-year-old superhero expert Mia Grace on a “Guardians” trivia challenge (above) during Monday's “Jimmy Kimmel Live.”

See video: ‘Guardians of the Galaxy’ 5-Minute Clip: Chris Pratt's Star-Lord Plots a Prison Break With a Raccoon and a Tree

Spoiler alert: They got smoked.

The cast of Marvel's Aug. 1 release hung out for most of the show, which was taped just before the movie's premiere at the El Capitan Theatre in Hollywood.

See video: ‘Guardians of the Galaxy’ Behind the Scenes: Chris Pratt Is Drawn to Character's Flaws

The evening also marked the first time Cooper met co-star Diesel, even though they play best buddies (a raccoon and a walking, talking tree thing, respectively) in the movie.

Watch them reveal the fun fact, plus more segments from the show, below: