It looked like The Late Late Show with James Corden turned into The Late Late Show with Alicia Keys as the Grammy Award-winning singer filled in for the absent host on Monday evening. Fans were in for a treat when pop star Billie Eilish visited the late-night talk show and chatted with Alicia, but they weren't expecting the two vocalists to join forces for a duet.

Fans began to cheer and clap as Alicia's hosting desk was revealed to be a piano and Billie inched closer and sat on the arm of the couch. Alicia then called for more dramatic lighting, so the stage darkened aside from vibrant blue lighting—a signature of Billie's. The all-female audience was then gifted with a duet from the two ladies who sang Billie's 2015 single "Ocean Eyes."

The song was written by Billie's brother, Finneas O'Connell, and was intended to be for his band. Instead, the track was intended to be used for a routine Billie was coming up for her dance class so she uploaded to Soundcloud with no intention of promoting it for any other purpose. The song quickly went viral and kicked off her career, so for the teen singer's fans, it's not only a walk down memory lane but a strange thing to see Alicia Keys belting out the tune alongside Billie Eilish. Watch their performance below.