"Thank you. Wow. I want to thank the fans because I tweeted about this a lot, I really really wanted this," she said. "I also want to thank the person that inspired this song, and he knows exactly who he is, because I got one of these!"
When Styles and his One Direction bandmates took the stage to present an award, the camera cut to Swift mouthing "Shut the f*** up" to BFF Selena Gomez.
At least Styles knew what he was in for.
It would be hypocritical for me to say she couldn't do it because everybody writes songs based on personal experience," he told Us Weekly last week.
"I can't say I'd have dated someone less famous to avoid it," he added.
Celebrity Couples of 2014 [PHOTOS]