CHICAGO, IL - AUGUST 01: Eminem performs at Samsung Galaxy stage during 2014 Lollapalooza Day One at Grant Park on August 1,
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Still scoring No. 1 hits after almost two decades in hip hop, Eminem has more than proven his longevity. But why he's stayed one of the scene's top players was more clear than ever as he closed Day 1 at Lollapalooza 2014

The rapper's headlining set sent social media ablaze when he surprised the crowd with an appearance by soon-to-be-tourmate Rihanna. (More on that momentarily.) 

But Marshall Mathers opened the set with a single spotlight shining solely on him. Casually dressed in shorts, a cap, zip-up hoodie and a T-shirt with LL Cool J's Bigger and Deffer (BAD) album cover on it, Em spit a no-frills snippet of The Marshall Mathers LP 2 intro track "Bad Guy" that set the tone for the entire performance.

With little fan interaction, Eminem paced the stage, more focused on technique than checking in on the crowd. Supported by hype man Mr. Porter and a full backing band, he knocked out snippets of semi-recognizable tracks like 2002's George Bush-bashing "Square Dance," his horror movie-referencing 2009 single "3 a.m." and 2003's upbeat "Business," while barely even looking at the crowd.

But the audience didn't need Em's constant attention. They were more than willing to support him through the first half of the set containing other semi-famous tracks, the most notable being recent MMLP2 single "Rap G-d." His 2000 hit "The Way I Am" signaled the halfway point of the set as well as Eminem getting more comfortable and, with that, turning to a more public-friendly section of the show.

Frequent collaborator Royce da 5'9'' came onto the stage dressed in a camouflage shirt and bright red hat. Together, he and Em performed "Fast Lane," a release off their joint Bad Meets Evil project. 

But that cameo was just a warm up. The stage went black for a second as the opening piano notes of "Love the Way You Lie" began playing. Soon enough, Rihanna herself emerged from the bottom of the stage in a sexy, cut-out dress and head wrap singing their No. 1 hit. 

Eminem and Rihanna are less than a week away from launching The Monster Tour, which they're co-headlining. So it was no surprise when the pop star stuck with Em to perform their newest collabo "The Monster." Em kept nailing his bars, with Rihanna watching on with respect, giving him space to do his thing. 

Then, before the singer slipped away, the two moved into Em's 1999 hit "Stan," with the Rihanna handling Dido's chorus. 

As the set moved on, Em looked more and more at ease talking to the massive crowd. He asked the audience twice, "Can we take it back to when I used to be f-cked up?," following up with some of his earliest smashes like "The Real Slim Shady," "Without Me" and "Not Afraid."

After finishing "Not Afraid," Slim thanked the crowd as if he was leaving, but you knew Em wasn't done. There was still a hit missing from his nearly 30-song setlist. Of course, that song was "Lose Yourself," performed with huge guitar screeching as the crowd shouted along to the chorus. 

In the final minutes of the encore track, Porter introduced the entire band by name. But no matter whose name was called or what other star had walked out on stage, there was one thing everyone in the crowd would have agreed on: This night belonged to Eminem.

Check back the whole weekend for all of Fuse's on-the-ground coverage from Lollapalooza right here.