The Dowager Countess won't be the only sassy, sharp-tongued senior giving orders when Downton Abbey's third season premieres in January.

At a TCA press conference in Beverly Hills Saturday, the newest member of the cast, Shirley MacLaine -- who will appear as Lady Grantham's mother, Martha Levinson -- opened up about the first time she ever met Maggie Smith, who plays the Dowager Countess.

"Well, we were lovers in another life," MacLaine joked to the crowd when asked if she had ever met Smith -- just before admitting that that was a slight exaggeration.

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Still, "We had met 40 years ago backstage at the Oscars, next to the catering table," MacLaine recalled. "I was up for something, and there was this big chocolate cake on the catering table. And whatever I was up for, I lost, and somebody else won. And Maggie said, 'You know what you did, dear? You tucked right into that chocolate cake and said, F-- it, I don't care if I'm thin ever again.'"

Added the 78-year-old MacLaine, "She remembered more than me, but then, she's younger than me. She's one year younger."

MacLaine also confessed she had an interesting epiphany on her first day about the social structure of early 20th-century England.

When she was in wardrobe, "The buttons were so small and located somewhere that I couldn't even reach. The corsets were so demanding. The zippers would have necessitated an attendant. And then I realized, 'Of course there's a class system. You can't get dressed without them!'" the actress quipped. Then, "I wondered which came first. Did they make a class system out of the necessities of the wardrobe, or was it the other way around?"

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And if it hadn't been for a trip to the hair salon, MacLaine revealed she might not have signed on to the Emmy winning series.

"I walked into my hairdresser lady in Malibu and they were all talking about [Downton Abbey]. [I thought], 'What do they mean? I better go look.' . . . then I saw it . . . and I was just as addicted as everybody else," she said.

After her friends at the hair salon described Lady Grantham's mother, MacLaine didn't have to think too hard when the drama's creators approached her about signing on.

"All the ladies in my hairdressing place said, 'Oh, [Martha] is Jewish and she's from Long Island and she has a lot of money and she's looking for a tight old man,'" MacLaine explained. "I thought that might be worth investigating."

This article originally appeared on Shirley MacLaine Jokes About Downton Abbey Costar Maggie Smith: "We Were Lovers in Another Life"