Emily Blunt has revealed that her The Devil Wears Prada costar Meryl Streep has lots to thank her for as she once saved her life.

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Blunt made an appearance on The Late Show with David Letterman and recounted the moment that occurred while they were taping Into the Woods.

"I did save her life. We were rehearsing a scene and she's playing a witch and she's supposed to jump on the table with a cape and everything. And I just saw this thing happen in slow motion. You know when something awful happens it's like the sound cuts out.

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"Meryl Streep's foot got caught in her cape. And we just started to watch her slowly topple head first toward the concrete floor."

She joked that their co-stars "froze" and that it was actually Blunt who lunged to catch her, even though she was pregnant at the time.

"She owes me big time," she said.

Blunt confessed that it is not too likely that Streep would have died, but she could have gotten hurt pretty badly.

"She's not ever supposed to die."

Blunt joked that she did think about letting her simply fall so "I could play the witch."

Before telling the story, Blunt dished on working with Streep.

"She's amazing it's annoying. She tormented me in [The Devil Wears Prada] now she's tormenting me in [Into The Woods]. I said this is it. You have to hate me. You can't have any other dynamic now."

She laughed and said one day she will play the "queen" while Streep portrays her "lonely dress maker."

Check it out.

Into The Woods hits theaters Christmas Day.