"Knock You Down" was the third single worldwide off of Keri Hilson's debut album, In A Perfect World. 

The song features both Kanye West and Ne-Yo. Along with Keri HIlson and the producer, Nate Hills, they collaborated on writing and recording the song.

Some reviews said the two male features overpowered Keri, however, I think they compliment each other perfectly in this song.

"Knock You Down" was nominated for Best Rap/Sung Collaboration at the 52nd Grammy Awards.  It also reached the top ten in Canada, Ireland, the United Kingdom, and the United States. Eventually "Knock You Down" peaked at #3 on the Billboard Hot 100 in the US.

Keri Hilson had previously been an established songwriter before her debut album. Ne-Yo, who took a similar path to making it big, had this to say about Keri,

"For one, I think Keri Hilson’s too freakin’ pretty to be in the background. For two, her voice is incredible—on top of the fact that she can write. So I think that she’s definitely one that deserves the spotlight."[1]

The song makes reference to Michael Jackson and eerily came out around the time of his death.