'You've made me cry again:' Christina Aguilera bursts into tears over Alisan Porter performance as final four sing on The Voice

Christina Aguilera sobbed openly as her contestant Alisan Porter brought the house down on The Voice on Monday night as the four finalists performed.

Alisan, a former child actress who played Curly Sue in the 1991 film, nailed the soaring Broadway classic Somewhere from West Side Story.

'You made me cry in the blind auditions and you've made me cry again,' sobbed Christina, 35.

Getting emotional: Christina Aguiler was overcome with emotion as her contestant Alisan Porter performed on Monday on The Voice

'I know how hard you've been working and…I feel you, if anyone deserves to take the cake and be the winner of The Voice, it's you Alisan,' she sniffed, wiping her eyes.

Adding: 'You are the definition of The Voice'.

'You are standing on top of the mountain right now, congratulations,' agreed Adam Levine, 37.

Alisan's performance took place during the first part of the two-part season 10 finale of the NBC singing competition show.

Wiped tears: The Genie In A Bottle singer wiped away tears as Alisan performed

Nailed it: Alisan brought her coach to tears by singing Somewhere from West Side Story

Each artist performed one cover, one self-written track and one duet with their coach.

The night kicked off with Team Adam's Laith Al-Saadi playing White Room by British rock supergroup Cream.

'Laith, I have no clue how to do what you do on the guitar,' marveled Christina.

Fourth finalist: Laith Al-Saadi was the first to perform after becoming the last singer to make the final four

'Who doesn't want to play air guitar after this guy's been on?' agreed Pharrell Williams.

'All I'm doing is enjoying my guy,' said Adam proudly.

Laith's second track was his original song Morning Light.

Peace out: The Michigan native performed his original song Morning Light

'I loved the bluesy slow jam part of it,' Christina told the 38-year-old Michigan native.

'Amazing chord changes,' said Pharrell.

'Slowly you've become my favorite…you've filled the room with joy,' beamed Adam.

Alisan's original track was called Down That Road and was inspired by her recovery from drug and alcohol addiction.

Red chairs: Adam Levine, Pharrell Williams, Christina and Blake Shelton critiqued the four finalists

Stunning performance: Alisan wore a sheer dress while performing during the penultimate show of the season

Visual rendition: The singer performed along with cool stage visuals

'You've just inspired me to finish up my album,' Christina told the 34-year-old Los Angeles mother.

'I would say that your voice, in a way, is the voice that deserves to win…if I'm judging it solely on that,' said Adam.

'You are the epitome of The Voice,' agreed Christina who is keen to win the title this season.

Blake Shelton hit the stage for a duet with Adam Wakefield as they took on The Conversation, a track by Waylon Jennings and Hank Williams.

Country star: Blake Shelton joined his contestant Adam Wakefield for a duet of The Conversation

Hannah Huston, 24, did an altered version of Every Breath You Take.

'That was so risky, but I think it'll be a huge reward for you,' said Blake, calling it 'brilliant'.

Pharrell praised Paul Mirkovich, who'd composed the new arrangement for The Police track.

Risky song: Hannah Huston took a risk with a stripped down version of Every Breath You Take

'That was beautiful,' Pharrell told his pupil, who hails from Nebraska where she's a teacher.

She also collaborated on a personal song with Pharrell called I Call The Shots.

Pharrell took the stage when she was finished to bow at her.

Worth it: The judges praised Hannah for taking a risk with a popular song

Hugged it out: Pharrell Williams went on the stage and hugged Hannah

Singing lesson: The Nebraska teacher got the crowd going

'One of the coolest things we've seen on the show, honestly,' said Adam.

Adam Wakefield, Team Blake's 33-year-old country/soul artist, did Lonesome Broken And Blue – a track he'd written on a beach with a margarita in his hand.

'So much colour,' said Pharrell while Adam chastised the audience for clapping in the wrong places.

Original song: Adam Wakefield performed his original song Lonesome Broken And Blue

'That was distracting me,' he complained.

'It took me back to the early 90s,' said Blake, comparing it to Keith Whitley.

Adam Wakefield, who lives in Nashville, then covered When I Call Your Name by Vince Gill.

Multiple talents: Adam also took to the piano to perform When I Call Your Name

'You're so talented,' said Christina, praising his ad-libs and runs.

'You have the most impeccable taste, the way you put together a song,' said Adam Levine.

Adam Levine sang and also played drums with Laith for a medley.

Teaming up: Adam Levine teamed up with Laith for a medley

Good times: Laith and Adam had fun while performing with each other

Christina's duet with Alisan was James Taylor's You've Got A Friend.

Pharrell's collaboration with Hannah was his hit Brand New.

The Voice finale concludes on Tuesday night on NBC.

Girl power: Christina joined Alisan for a duet of You've Got A Friend

Hit song: Pharrell and Hannah also teamed up for a duet of his hit song Brand New