As the "mockumentary" intro to Eminem’s set, a short film chronicling the life of the younger brother of fictional deranged fan "Stan,"signaled the beginning of Slim Shady’s set, thousands flocked across the field heading toward his set. While there were small gaps in the crowd around the muddiest parts of the field where the sludge was close to ankle deep, even with the weather, Eminem’s set likely drew one of the largest crowds ever at an ACL Fest headliner set.

"People are losing their minds over this Eminem (expletive)," a dude stumbling toward the porta potties after Major Lazer’s set remarked. Indeed they were. As I learned hanging out in Camp Stan earlier in the day, Em’s music has a special resonance for his fans. Also, as one young woman reminded me, he barely ever comes to Texas. His rabid fan base wasn’t going to pass on the chance to take in this rare appearance.

The crowd was thick all the way back to the RetailMeNot stage where fans watched from a distance enduring the thump on Skrillex’s bass for a less crowded vantage point. The grounds around RetailMeNot were particularly soupy from the rains, and in the dark many were slipping and sliding their way forward to find a location with less sound bleed.

The faithful were well rewarded, from Eminem classics like "Stan" and "The Way I Am" to more recent hits like "Toy Soldiers" and "Airplanes," Em led thousands in a sing-along, rap your heart out experience that will likely stick with his fans for years.