But it seems no one has taken to Season 4's new addition more than host Nick Lachey.
In this exclusive sneak peek from Monday's season finale (8/7c, NBC), Lachey reflects on their "magical season together" before busting into a swoon-worthy performance of "It Had to Be You." And Jewel is so moved by his efforts, she takes the stage and makes it a duet!
To hear what kind words Jewel had for Lachey and his dimples, and to see their impressive dance moves, check out the heartwarming clip below:
The Sing-Off airs Wednesday at 8/7c on NBC. The Season 4 finale airs Monday at 8/7c.