Country-pop sensation Taylor Swift performed on X Factor USA last night (November 15) and One Direction's Harry Styles was there to watch her rehearsal.

X Factor USA shared a tweet that explained the superstars were hanging out in the lunch line: "Together in the lunch line (Cheeseburgers) laughing & smiling was @Harry_Styles & @taylorswift13! :) #internationalpoproyalty"

Later in the day, X Factor USA then retweeted a message originally from @XFactorAccess that revealed the playful nature of the pair's growing friendship: "I saw @Harry_Styles throw @TaylorSwift13 over his shoulder to carry her out of her #xfactor rehearsal today! #CuteFactor."

The songstress treated the live studio audience and viewers at home to a rendition of her album track 'State Of Grace' and wore a white shirt, black tight-fitting trousers and a smart hat. Following her performance, she tweeted:

"Had a blast playing on #xfactorUSA. Also, @Ddlovato's hair looks SO good tonight."

Watch her X Factor USA performance here: