SPOILER: Which main vocalist put on 'Shangri-La' dance performance with VIXX's Ravi and Ken on 'Mask King'?

On the December 23 episode of the MBC singing competition 'Mask King,' eight new contestants battled for a chance to overthrow reigning king 'Eagle'!

One battle from the episode was between 'Chimney' and 'Fireplace,' who performed Jellyfish Entertaiment's agency-wide holiday single "Because It's Christmas" for the audience, surprising guest panelists Ravi and Ken of VIXX, who were a part of the song's original recording.

After the song was over, 'Fireplace' gave the audience and panel a hint as to what kind of celebrity he might be by putting on a small cover performance of VIXX's "Shangri-La" complete with his own paper fan. The dance was so impressive that Ravi and Ken also came on stage, each handed their own fan before joining him for an encore performance. Panelists could tell by just how easily he synced up with the other dancers that 'Fireplace' was most likely an idol too.

However, the audience vote revealed that 'Chimney' beat 'Fireplace', meaning 'Fireplace' had to drop out of the competition and reveal his identity.

The audience was surprised to find that 'Fireplace' was The Boyz member Sangyeon, who then went on to sing a moving cover of Brown Eyes' "Little By Little." During the reveal interview, he expressed regret over not being able to advance to the next round, saying: "It's a shame I wasn't able to show all that I practiced for my first time performing solo."

Check out Sangyeon's reveal video as well as his masked dance performance of "Shangri-La" here!