Love birds, Alex & Sierra, stunned the four judges on Wednesday's X Factor with two performances.

The duo first took the stage to sing Destiny's Child's Say My Name and added their own little flair to the 2000 hit. Alex & Sierra's rendition was so flawless that even former Destiny's Child member and current judge, Kelly Rowland, was impressed.

"I must admit I was not ready for that. It was a couple of moments in there where I was like, 'Is this my song?'" the singer said. "I was really shocked. But you guys really actually pulled that off."

Demi Lovato Performs Neon Lights On Season 3 Of X Factor

Demi Lovato also praised the couple and said: "I know you're not my category but I really want to see you in the finals."

Sierra then played the piano while Alex hit chords on his guitar as the couple took on A Great Big World and Christina Aguilera's new duet, Say Something. The 22-year-old's nailed it and received a standing ovation from all four judges.

"I feel like I was watching a performance on an award show," Rowland said. "I just saw a really, really big light for you guys and I think that's actually shine the best."

Lovato also went on to acknowledge the couple's true love, something she said they exuded with their performance.

"What I noticed when you guys sang that song, whether you meant to or not, you never took your eyes off of each other," Lovato said. "And it brought tears to my eyes because it's so beautiful and I really believe you guys."

The X Factor season 3 final four will be revealed on Thursday night's episode at 8 p.m. EST on Fox.

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