ONF made a stand on the March 16th installment of 'Immortal Song'.

On the special dedicated to ballad singer Jo Sung Mo, the boy group covered his 2000 track "I Swear" as the second performers up on stage. The ONF members expressed, "'I Swear' is Jo Sung Mo sunbae's only dance track, so I hope we can all dance together. I hope you look on us kindly because we've prepared better images." Laun also said, "Na Yoon Kwon sunbae did so well that we're really nervous. We were more focused on performance though, so we're hoping for a good result." 

However, ONF weren't able to take the round from Na Yoon Kwon, and it was Kim Yeon Ji who took the final win this episode. Check out ONF's rendition of "I Swear" and the original below!