With Team Xtina out of the competition, the Top 6 performed two songs each – one of their own choice and one chosen by their coach – on The Voice Monday.

Cee Lo, feeling under the weather over the past week, recruited Train’s Pat Monahan to step in as mentor to his team while he recovered, and Christina Aguilera threw her support behind Blake Shelton’s Cassadee Pope in tonight’s performance episode.

Top 6 Performances

Nicholas David

Twitter: @TheFeelin

The Minnesota soulman took on Earth, Wind and Fire’s “September” for his first song of the night. The performance seemed a little off as dancers boogied in the background and backup singers sang the most iconic part of the song. Nicholas returned to close out the night with his mom’s favorite song, Judy Garland’s “Somewhere Over The Rainbow,” from behind a red piano. Keeping just enough of the original melody, Nicholas put his own spin on the Academy Award-winning song.

Cassadee Pope

Twitter: @CassadeePope

Assigned another country song after her success with “Over You” and a performance with Rascal Flatts last week, Cassadee Pope put her pop rock spin on “Stand,” hitting some beautiful notes at the end. She returned later in the show with Avril Lavigne’s “I’m With You” – one of her favorites. Something about smoke on the stage and a long dress signals that a big moment is coming, but it was Cassadee’s voice that brought on the goosebumps during her final performance.

Amanda Brown

Twitter: @Amanda__Brown

Team Adam’s Amanda Brown has previously had more success with rock songs, but her gospel-tinged take on Aretha Franklin’s “You Make Me Feel Like A Natural Woman” proved she deserves a spot in the Final Four. Cee Lo’s “favorite mistake” returned to rock with Whitesnake’s “Here I Go Again” and showed her full range. Though it wasn’t quite “Dream On,” Amanda still blew the crowd away by hitting killer notes and obviously enjoying herself.

Terry McDermott

Twitter: @TerryMacMusic

The Scottish rocker stripped down Foreigner’s “I Want To Know What Love Is” for a moving, standing ovation-worthy performance accompanied by just a piano and cello (or a “big violin thing”/”Cee Lo,” as Blake put it). He took on Rod Stewart’s “Stay With Me” for his second song of the night, belting the song from the stands.

Trevin Hunte

Twitter: @Tamor_11

The 18-year-old from Queens took a break from the ballads for a fun, carefree performance of “Walking on Sunshine” (yes, you read that right) and even threw in a few dance moves. But it was Trevin’s emotional take on “And I Am Telling You I’m Not Going” that put him among not only the best singers in the competition but possibly in the industry. Cee Lo did a happy dance, Christina needed her fan even more than usual and we were left in awe that such beautiful sounds could come out of anyone’s mouth. As Pat Monahan said, “I hope Jennifer Hudson never hears that because she will quit this business.”

Melanie Martinez

Twitter: @MelanieLBBH

With a miniature piano, mannequins as her band and a change to her two-toned hair (blue and black), 17-year-old Melanie Martinez “Melanie-ized” Gnarls Barkley’s “Crazy” for her first song of the night. She stepped away from her darker, more somber choices with Lenka’s “The Show” as her second song. She didn’t seemed very connected to the song, but the staging made up for it.

Two more artists will go home on Tuesday’s results show, following performances by Ne-Yo and Matchbox Twenty. Vote for your favorites on Facebook, NBC.com, by purchasing a contestant’s song on iTunes (if an artist’s song is in the top 10 on iTunes, his or her votes will be multiplied by 10) or by phone or text (Sprint users only) until 10 a.m. ET Tuesday.

Who should move on to the Final Four next week? What was your favorite performance?