"I Knew You Were Trouble." Taylor Swift

You know dubstep has hit critical mass when even Taylor Swift is getting in on the action. The syncopated, bass-heavy EDM subgenre has been creeping into pop music for several years, but since Britney Spears' underrated "Hold It Against Me" kicked the trend into overdrive early last year, the number of wobbly breakdowns in mainstream music has exploded. They're smoothly and effectively put to use on Swift's latest pop single, "I Knew You Were Trouble.," which she debuted at last night's American Music Awards with a glitzy, production-laden performance. The wubbed-out chorus lends a bit of drama and edge to this otherwise perky lament of romantic abandonment, produced by Max Martin and Shellback. Much like the title's extraneous punctuation, the bass drops present a bold statement—of musical climax, artistic confidence, and potential new direction in the country princess' career. B+