Taylor Swift is known for bringing her celebrity friends to her concerts, and when she appeared at London’s Wembley Stadium to perform her 'reputation' World Tour, she needed someone special.
"When you are first starting out in something you want to learn from somebody who has done it before," she told the crowd.
"I'm so excited to call up somebody who has played Wembley bunches of times. London, would you be excited if I told you that Niall Horan is here."
The Irish One Direction member then joined her on stage to perform his hit song 'Slow Hands' alongside the American singer.
Niall Horan isn't the only special guest she's had this tour, also inviting Robbie Williams on stage with her to perform 'Angels' on another night of her London tour.