Sofia Vergara "popped" Reese Witherspoon's ovary.
The blonde actress urged her Hot Pursuit co-star to push her as hard as possible while shooting scenes for the movie, only for her to end up rushed to the emergency room when things got out of hand.
Witherspoon recalled: "We did a fight sequence, she's tough, man ... I might have had to go to the emergency room."
Vergara added: "Something with internal bleeding I push her and I push her and I kept telling her 'I think I'm pushing you too hard,' and she was like, 'No do it real'."
When she obliged, the 42-year-old actress left her co-star thinking she had "burst her appendix", prompting the hospital dash.
Sofia said: "I popped her ovary."
Elsewhere in the movie, Witherspoon, 39, had to speak in Spanish, much to the amusement of her Colombian co-star.
Speaking on The Ellen DeGeneres Show, Vergara said: "That was my favourite part of the movie, her speaking Spanish.
"Now I finally understand why I am so funny to the Americans."
And Witherspoon admitted Vergara couldn't fail to hide her scorn at her efforts.
She said: "She wasn't even nice about it. She was like, 'This is terrible. You sound terrible'."
- Bang! Showbiz