Tuesday night’s airing of The Tonight Show Starring Jimmy Fallon was lead by former First Lady Michelle Obama and an unknown second guest. It wasn’t until hours before taping that it was revealed that Ariana Grande would appear on the show. Serving as musical guest, the pop singer hit The Tonight Show stage to perform her new single “Imagine” for the first-time, with some help from The Roots. Ariana also joined Fallon, Horatio Sanz, Chris Kattan and Tracy Morgan to perform a reprise of SNL‘s holiday classic “I Wish It Was Christmas Today.”

Watch below.

Continue after the jump….

Previously:
Ariana Grande – “Imagine”
Ariana Grande – “thank u, next” (Video)
Ariana Grande’s “thank u, next” Debuts No. 1 on the Billboard Hot 100
Ariana Grande Performs “thank u, next” on Ellen (Video)
Ariana Grande Announces New Album, Drops “Thank U, Next”
Ariana Grande & Pete Davidson Break Up, Call Off Engagement
Ariana Grande Remembers Mac Miller: “I Can’t Believe You Aren’t Here Anymore”
Ariana Grande & Pete Davidson Are Reportedly Engaged