After teetering on the verge of elimination just a couple of weeks ago, Fifth Harmony entered tonight's (Dec. 19) 'X Factor' finals as one of the last three contestants. Can Simon Cowell's underdogs pull off a surprising upset?

The contestants all performed three numbers tonight — first revisiting a "song of the season," then singing a duet with a surprise guest, and finally closing out the night with one last shot at the title. Here’s how it broke down for Fifth Harmony:

First Song: 'Anything Could Happen' - Their first shot at this Ellie Goulding number was absolutely their best performance of the season, but they just did it a couple of weeks ago, which had the unfortunate effect of making tonight's reprise feel like a complete retread, right down to the same outfits and stage design. Still, they really do perform this song well -- and the judges knew it, too. "I don't know what you did, Simon," marveled L.A. Reid. "It's magical. I don't know what to say. You were the underdogs, and now you're the one to beat."

Duet: 'Give Your Heart a Break' - After reaching back to recent history for their first number, Fifth Harmony did it again their second time around, choosing the Demi Lovato hit they performed just a couple of weeks ago. It could be taken as a troubling hint that they don't have a lot to offer as a group -- again, this song works for them, and having Lovato join them on stage was a nice touch, but they might have been better served with something new to prove they have more to offer. "It pains me to say this," chuckled Cowell after it was over, "but Demi Lovato, you were sensational. Any time you want to join this group..."

Final Song: 'Let It Be' - After playing it safe with their first couple of songs, the girls closed out with a brave choice. Even if it's a song everyone knows, this Beatles classic isn't a natural fit for Fifth Harmony on paper -- but they brought something different to the arrangement, repeatedly riffing on the melody and adding a hip-hop beat to goose the rhythm behind a gospel choir. "I'm more than proud," concluded an emotional Cowell. "This has all come from you -- you're not a group, you're five great singers...I know I'm biased, but I really do believe that on the night, you deserve to win this competition."