Sam Fender made a surprise appearance during Olivia Dean’s headlining set at Lollapalooza on Saturday for a joint performance of “Rein Me In.” The rendition marked the first time Fender and Dean have played the song together in the U.S.“@lollapalooza that was mega,” Fender wrote in an Instagram post alongside footage of the performance. The performance comes after “Rein Me In” broke a 73-year-old British chart record in becoming the longest-running #1 single in the history of the U.K.’s Official Singles Chart. “Rein Me In” originally appeared on Fender’s 2025 album, People Watching. The duet version with Dean was later released as part of the deluxe version of the record.