"Heartbeat" is a song by Spanish singer and songwriter Enrique Iglesias. The song was written by Iglesias, along with his long-term collaborators Jamie Scott and Mark Taylor, for his ninth studio album Euphoria (2010). The mid-tempo ballad, produced by Taylor, features guest vocals from American singer Nicole Scherzinger. The song has a melody based on futuristic piano sounds and incorporates elements of dance music. The Rudi Wells' Open Heart Remix of the song later appeared on Scherzinger's debut studio album Killer Love (2011). The song was released as the album's third overall single, though it is the second English-language single, on 8 June 2010 in the United States and later in October 2010 France and the United Kingdom. Critics praised the song for the way that Iglesias and Scherzinger's voices complemented each other. An accompanying music video features the pair in emotive mood-lit scenes, where digitally produced colored heartbeats react as they interact with each and the lyrics of the song. Another version of the song titled as "Heartbeat (India Mix)" featuring legendary Indian singer Sunidhi Chauhan was included on a special Indian edition of Euphoria. Composition "Heartbeat" is a mid-tempo electropop dance ballad featuring a melody lead by futuristic piano notes. It was written by Iglesias, Jamie Scott and Mark Taylor, who also produced the song. Stephen Thomas Erlewine of AllMusic pointed out that the song had an "icy texture" while Becky Bain of Idolator noted that the duo's vocals carry much emotion. "Heartbeat" was also featured on Nicole Scherzinger's debut album, Killer Love (2011). The version featured on the album is the "Rudi Well's Open Heart Remix". Ellwood noted that the remix "added beats changing the tone of the song completely." and changed the song from dance, to more electronic rock and electro-industrial tendencies. The song is written in the key of B major. Critical reception Robbie Daw of Idolator called the song a "fragile and beautiful" track, whilst his colleague, Becky Bain, said that the song is a "perfect match for the duo's voices". Bain also said "['Heartbeat'] is thankfully kept under-produced, letting the emotions of both singers (who keep their vocals to a breathy, yearning coo) shine through." In his review for AllMusic, Stephen Thomas Erlewine said that the song is not an old-fashioned ballad, instead it "draws on the chilly textures of [singer-songwriter/producer] Ryan Tedder." Nick Levine of Digital Spy gave the song four out