Superstar Mariah has been performing a string of Christmas-themed concerts at the historic Beacon Theatre, and it looks like Gaga got a front row seat last night (22 December).
Posing together for a photo backstage, Gaga said: "Hey ladies, Merry F***ing Christmas. Love, Mariah and Gaga. This lady is so kind, such a star, and sounding legendary tonight at Beacon Theatre."
Both Mariah and Gaga looked super glam, and after seeing the photo, fans began asking if a duet was on the cards!
Sharing another photo, Mariah said: "Taking a selfie with the beautiful @ladygaga! Merry Christmas!"
It was an iconic performance for Mariah, who told fans that her festive 1994 hit 'All I Want For Christmas Is You' has racked up 100 million views on VEVO.
Mariah wrote on Instagram: "Excited and blessed to wrap up my final show at the Beacon Theatre and find out that 'All I Want For Christmas Is You' is now VEVO certified for 100 million views!
"Thank you for spending the last week with me at my Christmas concerts, it was an incredible experience and I already can't wait to do it again next year. MERRY CHRISTMAS EVERYONE!"
Last week, 'Heartbreaker' singer Mariah told fans that she was officially in the Christmas spirit after dazzling crowds in a plunging red embellished gown and slinky silver dress.
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Watch Mariah's video for 'All I Want For Christmas Is You' below: