Upon the release of the single, Avicii claimed that Lewis and her record label, Syco, had sampled his song "Penguin" without his authorisation, and accused them of plagiarism.

"Collide" was released digitally via the iTunes Store on 2 September, as part of a collection of the original song, as well as remixes by Afrojack, Cahill, Alex Gaudino and Jason Rooney.

Some were complimentary of Lewis's vocal performance and compared it to Katy Perry's song "Firework", whilst others were critical of its musical structure.

The song achieved commercial success, and peaked inside the top five of the singles charts in Ireland, Scotland and the United Kingdom.

As part of promotion for the song, an accompanying music video was shot on a beach in Malibu, California and directed by Ethan Ladder.

Lewis began planning her third studio album Glassheart in June 2010, shortly after completing her first headline tour: The Labyrinth.

"[3][4] With regard to the song, Lewis spoke about "Collide" and why she chose to release it as the lead single, saying I'm excited for people to see a different side to my music.

[7] Glassheart was originally set to be released in November 2011 following "Collide",[8] however the album was subsequently pushed back several times into early 2012,[9] then Summer 2012,[10] before settling in October 2012.

[11] Soon after "Collide" premiered, the song received comparisons to an instrumental dance track called "Penguin" by Swedish DJ and recorded producer Avicii.

[12] According to Avicii's manager Ash Pournouri, he thought that Lewis was going to only sample the original version by Penguin Cafe Orchestra.

The original sample rights belong to Simon Jeffes (Penguin Cafe Orchestra) and approval for using that composition is not in our control.

"[12] As part of the lawsuit for not receiving credit on "Collide", Avicii attempted to have the release of the song suspended until an agreement was reached.

[20] Lyrically, "Collide" is a love song, in which Lewis sings "I'll pick you up when you're down / Be there when no one's around / I'm in tune with how you feel / Everything 'bout this is real / When you're in unfamiliar places / Count on me through life's changes.

[20] Amy Sciarretto for Popcrush was complimentary of Lewis's vocals, writing that she sounds "appealing and captivating," and continued to say that it is what her fans have been waiting for.

[22] St. Asaph wrote "The lethargic, two-note verses make her voice sound less husky than bored, an emotion that a comeback single should never evoke.

[18] Cragg continued to say that Lewis does a "passable job as a dance diva," and noted the resemblances between "Collide" and "Penguin".

[18] "Collide" made its first chart appearance in the United States, where it debuted on the Dance Club Songs at number 32 for the week of 20 August 2011.

As of December 2013, Lewis holds the record for British female solo artist with the most UK Top 5 singles, with eight.

[43] For the most part of the video, Lewis is featured on a beach in a variety of different settings, such as sitting in an old cabriolet car, in which she is surrounded by her friends.

"[44] Robbie Daw for Idolator compared the "party in the sand imagery" to Katy Perry's music video for "Teenage Dream".

[48] She performed the song as part of a set list with a cover of Diddy – Dirty Money's "Coming Home", who she was joined on stage with by Wretch 32, "Better in Time", "Come Alive", a new song which she premiered from Glassheart, "Bleeding Love" and "Run", who she was joined on stage with by the Hackney Community Choir.