Luke Hemmings, Ashton Irwin, Calum Hood and Michael Clifford of 5 Seconds of Summer

How 5 Seconds of Summer Perfected One Direction's Rock-First Formula

Top 40 fans are ready for a mainstream rock revival after digesting electro-pop and EDM for years. One Direction has certainly helped speed up that transition, and now 5 Seconds of Summer -- who can emphasize good guitar-playing as well as good looks -- is reaping the rewards, in a big way.