"You Lost Me" is a song by American recording artist Christina Aguilera from her sixth studio album Bionic (2010).

The track is a down-tempo ballad that talks about an unfaithful man, who has left Aguilera's world "infected".

[1] "You Lost Me" was well received by most critics, who noted it as one of the album's outstanding songs and praised Aguilera's vocals on the track.

In August 2008, Australian singer Sia confirmed that she would work on several ballads for Aguilera's then-upcoming album.

[1] Amar Toor from AOL Radio thought that its lyrical content "perfectly captures one of the most difficult experiences young lovers have to go through".

[18] The song begins with a "somber orchestral" piano opening, followed by the lines "I am done, smoking gun/ We've lost it all, the love is gone" sung by Aguilera.

Leah Greenblatt from Entertainment Weekly noted Furler's efforts on the "lovely" ballads "You Lost Me", "All I Need", and "I Am" had turned Aguilera into a "smoky, almost Fiona Apple-esque torch singer".

[17] Lindsay Zoladz, an editor of the Canadian magazine Cokemachineglow, wrote that the song was an "absolute stunner", adding that "her [Aguilera's] voice, minimally adorned, is free to showcase her amazing sense of control and kindle a subtle spectrum of emotion".

[25] In his revision for Entertainment Focus, Gary James called it "sublime" and opined it was impressively sung by Aguilera.

[29] In his 2020 retrospective commentary on the album Bionic, Billboard's Glenn Rowley celebrated "You Lost Me" as a "soaring, oft-overlooked ballad".

[30] Daniel Megarry of the Gay Times complimented the song, calling it "a gorgeous, heartbreaking ballad about unfaithfulness that showed off the softer side of Christina’s legendary voice".

[31] Entertainment-related website Tan's Topic called it a "masterpiece", and recommended the official Hex Hector/Mac Quayle remix of the song.

[47] During the making of the video, Aguilera said, "It was really important that I interpret the simplicity of the raw emotion that takes place within the song itself and not any sort of theatrics involved".

[48] According to Billboard writer Monica Herrera, the clip contrasts with the music video for the lead single of Bionic "Not Myself Tonight",[19] while Chris Ryan for MTV Buzzworthy thought that it goes "back to basics".

[48] The clip ends as Aguilera takes off her shirt in an "Inception-like dreamworld" as her black clothing turns to white.

[50] Critical response to "You Lost Me" video was positive: Latina writer Mariela Rosario and UK magazine OK!

[53][54] In May 2020, as a result of the "#JusticeforBionic" social media campaign, the song's music video reached number one positions on the iTunes Top 100 Videos charts in multiple countries, including Brazil, France, the Philippines, the United Kingdom, and the United States.

[61][62] On June 8, 2010, Aguilera performed the song again — during The Today Show — with several of her tracks, "Fighter", "Bionic", "Not Myself Tonight", and "Beautiful".

[63] According to James Dinh from MTV News, the performance of "You Lost Me" "brought a subtle and gentle ambience" to the show, and it was not aired on television.

[64] A day later, she appeared on The Early Show to promote her then-upcoming album Bionic, performing "Not Myself Tonight", "Fighter", "You Lost Me", and a medley of "Genie in a Bottle" and "What a Girl Wants".

It features a cameo from Aguilera who performs "You Lost Me" at Ari Gold's (Jeremy Piven) party.