6:32am PT by Erin Carlson
'Downton Abbey' Sneak Peak: Shirley MacLaine Takes on Maggie Smith (Video)
Finally, the moment Downton Abbey superfans have been waiting for: the first withering encounter between Maggie Smith and Shirley MacLaine, who makes her debut in season three of the PBS hit series.
A clip of MacLaine's debut as the Martha Levinson, the American mother of Lady Grantham (Elizabeth McGovern), was shown during the American Film Institute's televised tribute to the actress, broadcast Sunday on TV Land.
The scene shows Martha visiting Downton Abbey, where she encounters Smith's quippy Countess of Grantham.
"Oh dear, I'm afraid the war has made old women of us both," she says, to which the Countess responds: "Oh, I wouldn't say that. But I always keep out of the sun."
The Oscar winner's addition to Downton makes her the second American cast member (and character) on the British period drama. The third season is slated to roll out in early 2013.
Watch the video below.