We're down to the final four on this season of 'X Factor,' and tonight (Dec. 12), the contestants were tasked with performing two numbers -- one that they chose themselves, and one picked with their mentors in order to get them into the finals. They all came out swinging, but who connected and who whiffed? Let's take a look.

Tate Stevens: Tate picked Craig Morgan's 'Bonfire' for his first number, and he knows what he's doing -- this song sits right in his sweet spot as a singer and a performer. Taking command of a stage decked out with tires, Stevens looked like he was having a great time, and for good reason: 'Bonfire' might have been his best performance of the competition. Judge Britney Spears disagreed, saying "I don't think it was your best," but everyone else was on board, including Demi Lovato, who called it "freaking amazing" and added, "Not only did it totally bring me home and make me feel like I was in Texas, but it was a winning performance. It really was."

For his mentor-chosen number, Tate returned with Clay Walker's 'Fall,' a soaring love song that doesn't particularly stand out from any other ballad playing on any random country station right now, but one given added resonance thanks to Stevens' soulful performance -- and his revelation that he was dedicating it to his wife, with whom he's celebrating 15 years of wedded bliss this week. "Your wife must feel like the luckiest girl in the world," cooed Lovato, while Cowell chuckled, "There's about as much chance of you going back to your old job as there is of me flying to the moon tomorrow night."

Carly Rose Sonenclar: At this point in the competition, the contestants and their mentors need to be really smart about finding the line between sensible song choices and safe, predictable ones -- and at first glance, Carly's choice of Elton John's 'Your Song' seemed to fit squarely in the latter camp. But just as she's done pretty much every other week, she rose above and beyond the occasion, taking full possession of a song most people have heard more times than they'd like. Reid agreed, pointing out, "You picked a very, very risky song," then adding, "having said that, you did things with that song I've never heard done before, and I could feel you wanting to win this competition."

Spears has made a point of choosing difficult songs for Sonenfeld to perform, and she lived up to expectations with her second number of the evening: John Lennon's 'Imagine.' Not only did she pick a signature classic by a former Beatle, she tasked Sonenfeld with playing the piano while singing it -- but if Carly really felt the nerves she hinted at in the pre-taped segment, she didn't show any sign during a rendition that made room for the original's tender intimacy while adding plenty of the melismatic bombast that contests like 'X Factor' require. After criticizing her for being "predictable" earlier in the night, Lovato smiled and said, "The only predictable thing about that performance was that it was going to be amazing."

Emblem3: The guys chose Peter Frampton's 'Baby I Love Your Way,' explaining it had some personal meaning thanks to its constant spot in the heavy rotation of their childhood. Then they took the stage and gave the classic rock chestnut their Emblem3 spin, adding a hip-hop beat and rap breakdown to go with their signature sunny harmonies. And they worked the stage, too, causing constant detractor Lovato to cheer, "That's exactly what I was talking about." Added Cowell, "You chose a fantastic song. If this doesn't get you into the finals, nothing will."

Perhaps figuring one rock classic deserves another, Cowell chose the Beatles' 'Hey Jude' for Emblem3's second song, a notably risky pick -- and the guys came through with flying colors, delivering a smartly subtle rendition of a song that didn't need any hip-hop production gewgaws or rap breakdowns. "I was prepared to rip you to shreds," admitted Reid, but said they lived up to the song's original artists: "You actually are teen heartthrobs like the Beatles." While Lovato cautioned that she wouldn't go quite that far, she was still full of praise, telling the guys, "You have the potential, seeing the fanbase you have. It's crazy."

Fifth Harmony: Simon's five-piece girl group was up against the wall this week, having only escaped elimination last week thanks to Diamond White's unfortunate exile from the competition. But they strutted right back from the edge with a brilliant performance of Ellie Goulding's 'Anything Could Happen,' showing up with an inventive stage design and cool, quirky visual vibe to match their interesting arrangement of Goulding's song. Reid has given the girls a hard time in the past, but he had nothing but praise for them this time around, calling it "the very best vocal performance you've ever done."

In comparison, their follow-up number seemed a little underwhelming, thanks to Cowell's choice of the song they performed when they auditioned for him all those weeks ago: Shontelle's 'Impossible.' They're obviously more polished performers at this point -- and they added Spanish lyrics in a nifty twist -- but it was a case of "been there, heard that" for most of the judges. "I think the song choice was a little bit lazy because you've done it before. I've heard it," sighed Reid, while Spears was even more blunt: "I would be really surprised if you guys are here next week."

Now it's up to the voters to decide who makes it to the finals and who goes home -- and we'll find out what they decided tomorrow night (Dec. 13) during the 'X Factor' results show.