Amy Poehler and Tina Fey are "each other's chosen sister."
The comediennes, who have been friends for 20 years and play siblings in the upcoming film 'Sisters,' say they always lean on each other for support and advice.
Amy, 44, said: "Neither Tina or I have sisters in real life. We are each other's chosen sister. Like most sisters, we've never dated the same guy and we're great in photo-shoots and fittings because we know what will look good on one another."
The 'Parks and Recreation' star says they also rely on each other to vent about the problems they encounter in Hollywood.
She said: "We're kind of like sisters and our parents are show business. We call each other to complain about how mom and dad have treated us at Thanksgiving."
The pair love working together and have hosted the Golden Globes together twice in past so Tina, 45, didn't hesitate to ask Amy to play her sister after she signed on to produce and star in their new festive film.
She told Entertainment Weekly magazine: "It just wouldn't make sense playing sisters with anyone else. There's an ease that we have with each other."
The duo first met as young performers at Chicago's ImprovOlympic when owner Charna Halpern recognised they had a lot in common.
Writing in her 2014 memoir, 'Yes Please,' Amy recalled: "Charna took a liking to me, and me to her. She told me I was just as good as the big boys. She believed in me. She said there was another new improviser in another one of her classes whom she thought I would really like. Her name was Tina and she was like me but with brown hair."