At Rock in Rio on Saturday, Sept. 28, Weezer ended their set by playing a cover of Nirvana's "Lithium" as a teaser for fans who would be watching headlining band Foo Fighters play. According to Loudwire, later in the Foo Fighter's set, Dave Grohl mentioned the cover by saying, "I was backstage and I heard Weezer play the ‘Lithium’ song," Grohl told the crowd, continuing, "I gotta be honest, I cried a little bit. I did! I miss playing that song. I miss it, so I’m happy to hear Weezer play it again. So this one goes out to the sweet Weezer."