"Knock You Down" is the fourth U.S. single from Keri Hilson's debut album, In a Perfect World.... The song features rapper Kanye West and R&B singer Ne-Yo.
The music video for the song premiered on March 23, 2009, one day before the release of the album. The song was released as the second single in the United Kingdom on 22 June 2009.
The song is Hilson's most successful single as a lead vocalist peaking at number 3 on the U.S. Billboard Hot 100 chart and number 5 on the UK Top 40, making it her 2nd top 10 single overall, after "The Way I Are", with her associate D.O.E. and musical mentor Timbaland both in the US and UK. The single was certified Gold by the RIAA and the RIANZ.
Listen to the track below: