System of a Down were the headlining act for Rock in Rio Brazil last night (Sept. 24), playing for a seriously ridiculous number of people. During the band's near two-hour set, System invited Deftones frontman Chino Moreno onstage to help sing "Toxicity."

Every edition of Rock in Rio gives us an insane sense of jealousy, because the event is beyond epic every single time. The Sept. 24 festival date featured System of a Down, Deftones, Queens of the Stone Age, Lamb of God, Halestorm, Hollywood Vampires and many more, and that's just one of seven days!

Guitarist Daron Malakian called Moreno "a longtime brother of System of a Down" as the Deftones vocalist approached the stage to hug Serj Tankian. Chino and Serj switched off on the "Toxicity" verses and chorus, with Chino even lending his signature scream to the track. Right before the song's bridge, Malakian commanded the mammoth crowd to break off into multiple circle pits, which was caught on camera as an awe-inspiring sight.

Watch System of a Down's Rock in Rio performance in the video above! We've queued it up to the performance with Moreno, but go back to 0:00 to watch the entire set.

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