Eminem stunned a crowd last night at New York's Bowery Ballroom, taking the stage for a secret performance at the end of a long night of battling MCs that also featured a set by Slaughterhouse. The occasion was Red Bull's Emsee Battle: The Road to 8 Mile -- a multi-city tour that pits battle rappers against each other in the ultimate cross country fight for supremacy on the mic.

The night kicked off around 10PM with eight MCs vying for the New York title. Within an hour, the field was narrowed down to two finalists named Quest MCody and DNA. The two rappers went hard at one another in a multi-round finals battle that showcased impromptu freestyles as well as classic battle spitting. DNA emerged as the clear victor as chosen by judges Just Blaze, Alchemist and Craig G.

By this point, the intimate crowd, which included host Angela Yee and a robust guest list with people like Bun B, Rhymefest and Jeffrey Wright, was surely live and knew some special guests were in order. The full Slaughterhouse took the stage one-by-one and sliced through a set of numbers off their debut album. Soon enough, anticipation for the biggest surprise of the night grew when Alchemist (also Eminem's DJ) started setting up behind the turntables.

Eminem, whose 'Recovery' album is in stores today, finally appeared to absolute pandemonium. In such a small venue with such a surprised crowd, Shady put on an energetic secret performance, ripping his 'Despicable' freestyle on top of Drake's 'Over' beat before putting in a turn on 'Beamer, Benz or Bentley' and then barreling through some 'Recovery' hits like 'Won't Back Down.' It was a legitimate once-in-a-lifetime chance to see the last decade's biggest seller rock what must have been one of his smallest crowds since the late '90s.