Kristen Stewart claims she punched Chris Hemsworth by mistake during a battle sequence in Snow White and the Huntsman.

The 21-year-old starlet is currently filming the fantasy film, and a fight scene went awry, leaving the Hollywood hunk with a black eye and a “big lump on his nose.”

Though most of the focus on Stewart’s guest appearance on Thursday night’s “Tonight Show” was, predictably, on her upcoming new “Twilight” film and the nearly-R rated sex scene that will be discussed ad nauseam for the next few weeks, she was able to sneak in a promotional tease for “Snow White and the Huntsman,” the radical retelling of the old fairytale in which she plays a princess who transforms into a warrior.

Chris Hemsworth, who is most known for his portrayal as “Thor” last summer, plays the Huntsman, who was sent to murder the princess but instead became her tutor in the wild, and while he is a rock of a human being, Stewart reveals that she got the best of him with a smack, albeit unintentional.

“It made such a sound!” she exclaimed as she punched the air. “Girls, if you’ve ever wondered if it works — it works! I mean, it literally spun him right around. It was crazy.”

“I was supposed to miss him by this much,” Stewart said excitedly. “I  basically knocked him right out of his close-up. I mean, I’m not proud, though. Instantly tears sprung to my eyes. I’m like, ‘Are you OK?’”

The sudden and fleeting remark of worry didn’t convince Leno.

“Not proud?! You were just bragging!”

Maybe she got a little carried away with her vengeance?

Stewart remarked at Comic-Con this summer, “I wasn’t initially jumping at the chance [to play Snow White], but she is one of the most heavy-handedly sincere, seriously doesn’t let her heart cloud her mind characters. Also, I get to have a sword and stuff.”

Stewart is attempting to flee the hands of Charlize Theron’s wicked Queen Ravenna, who wants to devour her heart in order to become immortal.

In the film, Chris, 28, plays Eric, the Huntsman, and it will be released in June 2012.