Taylor Swift dissed ex-boyfriend Harry Styles at the 2013 VMAs

Taylor Swift is up to her old tricks again. The 23-year-old pop star -- known for writing those infamous breakup tunes -- dissed One Direction's Harry Styles, this time at the 2013 MTV Video Music Awards at the Barclays Center in Brooklyn, N.Y.

When Styles and his One Direction bandmates presented an award onstage, Swift (sitting with BFF Selena Gomez) was filmed mouthing "shut the f--- up!" in the audience. Swift previously mocked Styles by speaking in a British accent during her "We Are Never Ever Getting Back Together" performance at the Grammy Awards in February 2013. The couple called it quits during early January after a couple months of dating.

Later in the evening, the entertainer won big for her "I Knew You Were Trouble" hit, which was inspired by her split with another high-profile man in her past -- presumed by some to be late-2010 fling Jake Gyllenhaal.

"Thank you. Wow. I want to thank the fans because I tweeted about this a lot, I really really wanted this," she said in her acceptance speech for Best Female Video. "I also want to thank the person that inspired this song, and he knows exactly who he is, because I got one of these!"

Styles quietly looked on from his seat in the audience. The "Best Song Ever" singer revealed in Us Weekly's latest issue that he fully expects Swift to write songs about him for her next album. "It would be hypocritical for me to say she couldn't do it because everybody writes songs based on personal experience," he told Us exclusively. "I can't say I'd have dated someone less famous to avoid it."