Nashville rockers' Kings of Leon kicked off Global Citizen Festival with a tight, high-energy set. The two-year hiatus seems to have effectively re-energized the band. Instead of an exhausted, by-the-numbers set like their live show circa 2011, you could tell they actually enjoyed rocking out together. Frontman Caleb Followill jokingly apologized for his family members' "sloppiness" before they launched into "Beautiful War," a highlight from Mechanical Bull. And obviously, they did "Sex on Fire." Watch it below.