The image from "Joker: Folie à Deux" shows Gaga's character in an embrace with Joaquin Phoenix's Joker.
Gaga's only comment was the sequel's title. "Folie à Deux" and a joker's hat emoji.
Director Todd Phillips, who helmed 2019's dark villain origin tale "Joker," posted the same image to his Instagram page with the caption, "Happy Valentines Day."
Gaga worked with Phillips on her starring role in "A Star Is Born," which Phillips produced. Filming for the Warner Bros. "Joker" sequel is underway in New York and Los Angeles, set for an Oct. 4, 2024 release date.
It has not been confirmed what role the singer/actress will be taking on. But a teaser released last summer offered a clue that she may be starring as Batman villain Harley Quinn, a character most recently played in several DC movies by Margot Robbie.
Catherine Keener and Brendan Gleeson have also joined the "Joker" sequel, along with Zazie Beetz, who returns from the 2019 film.
Lady Gaga confirms 'Joker' role: She will star opposite Joaquin Phoenix, as new teaser shows
Phillips' original "Joker" followed Phoenix's troubled aspiring comic Arthur Fleck on his downward spiral transforming to the iconic DC villain.
"Joker" grossed over $1 billion in worldwide box office, becoming the highest-grossing R-rated film in history. The critically acclaimed film earned 11 Oscar nominations, winning two awards – Phoenix won as best actor and Hildur Guðnadóttir took best original score.
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The sequel title, "Folie à Deux," is a reference to a medical term for a mental illness shared by two people in close association.
This article originally appeared on USA TODAY: 'Joker 2' first look: Lady Gaga, Joaquin Phoenix revealed in dark embrace