Jimmy Fallon has a new duet partner. 

On Tuesday's "Late Night," the host teamed up with guest Selena Gomez to sing his revamped version of a YouTube song by Sam Hart called "Mario Kart Love Song." 

Fallon called the original "the greatest love song of all time," explaining that it "combines the timelessness of love with the timelessness of Mario Kart."  But he said he thought it should be a duet, so he "wrote up some new verses from the female perspective."

They enhanced their performance by singing dressed as Mario and Princess Peach.  Selena appeared on "Fallon" to promote her new film, Spring Breakers.

Check out the video: