5 Seconds of Summer made two surprise-linked appearances at Lollapalooza in Chicago, joining singer sombr on stage and performing a rock version of Katy Perry’s “Teenage Dream” during their own set. The moments highlighted the band’s return to live festival performances following the release of its latest album and added to the opening night’s guest-heavy atmosphere.

At sombr’s set on 30 July, Luke Hemmings, Michael Clifford, Calum Hood and Ashton Irwin provided backing for a version of 5SOS’s 2014 hit “She Looks So Perfect”, which reached No. 24 in the US. Their new album, Everyone’s a Star!, debuted at No. 6 on the Billboard 200; the group has previously topped that chart three times. Lollapalooza continues through the weekend with artists including Tate McRae, Charli xcx, JENNIE and Olivia Dean.