SLIPKNOT kicked off its headlining stint at this year's Rockstar Energy Drink Mayhem Festival yesterday (Saturday, June 30) at San Manuel Amphitheater in San Bernardino, California without guitarist Jim Root, who is out of action while recovering from a burst appendix.

The band's setlist was as follows:

01. (sic)
02. Eyeless
03. Sulfur
04. The Blister Exists
05. Wait and Bleed
06. Before I Forget
07. Disasterpiece
08. Gently (performed live for first time since 2002)
09. Vermilion
10. Pulse of the Maggots
11. The Heretic Anthem
12. Psychosocial
13. Duality
14. Spit It Out

Encore:

15. People = Shit
16. Surfacing

Fan-filmed video footage of the concert can be seen below.

Yesterday's Rockstar Energy Drink Mayhem Festival concert in San Bernardino had a record-breaking attendance of 26,105 — 4,000 more than the previous attendance record set by the tour.

In an interview with Loudwire, SLIPKNOT percussionist Chris Fehn spoke about working without Root and how it's hard deciding which songs to play in the set. He explained, "It always is [tough] when you've got more than one or two records, and it's hard for us to do live too. We're not sure what we want to do new and what we can play live, what we can't play live cause a lot of it has to do with Jim not being here and stuff like that, which is a big hole in the SLIPKNOT camp right now, but it's always a good problem to have [deciding which songs to feature]. Sometimes what we want, what the fans want, it's a whole different situation. It is difficult, but there'll be more to come."

SLIPKNOT began its return last summer with a European tour, continued it earlier this year with jaunts through Australia and South America, and will now complete it this summer with a headlining slot on the Rockstar Energy Drink Mayhem Festival. The icing on the cake will be Knotfest, two festival dates put together by the band itself on August 17 in Council Bluffs, Iowa and August 18 in Somerset, Wisconsin.

In addition to the headliners, both days will include sets from DEFTONES, LAMB OF GOD, DETHKLOK, SERJ TANKIAN and PRONG.

Also playing at the Iowa show will be THE URGE and DIRTFEDD, while the Wisconsin show will also feature CANNIBAL CORPSE, GOJIRA and THE DILLINGER ESCAPE PLAN.

Knotfest is being positioned as a "dark carnival experience," and the event will feature circus tents, pillars of fire, amusement park rides, burlesque performers, fire-breathers, stilt walkers, drum circles made of junkyard cars, graffiti walls and even a SLIPKNOT museum.

The festival will mark the end of a two-year grieving period for the band following the May 2010 death of bassist Paul Gray from an overdose of drugs.

SLIPKNOT will tentatively enter the studio sometime in early 2013 to begin recording its fifth album. In the meantime, a greatest hits collection called "Antennas To Hell" arrives on July 24.

SLIPKNOT will also release its first-ever mobile app, Wear The Mask. The app will be made available simultaneously with "Antennas To Hell" and is marketed as part mask builder, part social connector for fans.