Numb/Encore is the first and only official CD single to come from "mash-up" album Collision Course, featuring a collaboration of tracks from Linkin Park and rapper Jay Z. Numb (taken from 2003 album Meteora) & Encore (taken from 2003 album The Black Album) were amongst other tracks remixed together and then performed live in front of an audience at The Roxy.

The track reached #20 on the US Billboard Hot 100 & peaked at #14 on the UK Singles Chart, in which it holds the record for being the longest stay in the top 20 without ever reaching the top 10, at 13 weeks.

The video was directed by Kimo Proudfoot and features a collaboration of footage from the performance of the song at The Roxy, and behind the scenes footage of the making of the album, which can be seen on the DVD available with the album in stores.