B1A4's Sandeul and CNU covered Lee Mi Ja's "Because You Might Not Come" on the March 15th episode of 'Immortal Song 2'.

SEE ALSO: B1A4 celebrates 13th anniversary with sold-out fan concert series

The two singers mixed the original, melancholy song into a more upbeat, lively track. The two members had perfect harmony, and Lee Mi Ja commented, "I want to compliment you. It's not easy to harmonize, but you did it perfectly."�

However, Sandeul and CNU lost to Gummy's 381 points, and Lee Se Joon�won the final trophy.

Watch the duo's performance, and let us know what you think!