If you have any doubts about whether old Slim Shady was back, all you need to do is read the lyric sheet to Eminem's just-dropped "Berzerk" for confirmation.

Unlike some of the more somber work from his Relapse and Recovery albums, "Berzerk" is an unqualified return to the Em of old, complete with the celebrity dis, one of the signature pieces of such early songs as "The Real Slim Shady" (Christina Aguilera), "My Name Is" (Pamela Anderson), "Marshall Mathers" (P. Diddy) and, more recently, "We Made You" (Kim Kardashian).

The first single from the upcoming The Marshall Mathers LP 2 debuted on Monday night on Slim's Shade 45 Sirius satellite radio station. Produced by Rick Rubin, it contains the former Def Jam co-founder's trademark mix of big beats and rock samples, including "The Stroke" by Billy Squier.

Shouts to Kendrick and PE
Before he gets to the dissing, though, Eminem gives props to some of his hip-hop brethren, including Kendrick Lamar ("'bout to go ham, ya bish, shout out to Kendrick"), as well as N.W.A.'s MC Ren ("the art of MCing mixed with da Vinci and MC Ren") and legendary lyrical bomb-throwers Public Enemy ("Been public enemy since you thought PE was gym, bitch.")

Your Complete GIF Guide To Eminem's 'Berzerk' References.

Shots at K-Fed, Lamar Odom
And then it's time for the bodies to fall. Taking aim at one of his favorite past targets, Britney Spears' corpulent ex Kevin Federline, Em goes all in on the one-time tabloid staple who has faded from memory over the past few years. "So baby just make like K-Fed and let yourself go, let yourself go," Em raps in the song's hook in reference to Federline's increased waistband.

The other major shot in the song is at the expense of the kind of celebutants Shady has often taken down before (see: Kim Kardashian in "We Made You"). In fact, Em has moved on from Kim to sister Khloe and her troubled husband, NBA player Lamar Odom.

The song was clearly recorded before the news emerged last week that Odom was reportedly struggling with substance abuse issues, making the sting of Marshall's lyrics that much more painful. "They say that love is powerful as cough syrup and Styrofoam/All I know is I fell asleep and woke up in that Monte Carlo," he raps. "With the ugly Kardashian/Lamar, oh sorry yo, we both set the bar low."

Future fire?
Another target is the trickiest one to figure out, as there's no known prior beef between Eminem and rapper Future. "Bars hard, drugs hard thought that's the past/But I done enough codeine to knock Future into tomorrow," he rhymes in a couplet that's not so much a dis as just a bizarre shout-out.

Birdman gets a nod
The final name dropped is that of Cash Money domo Birdman, who shows up in the waning minutes of the song. "You bird-brained baby I ain't called anybody baby since Birdman," Em raps.