Two of our favourite heartthrobs [1] just shared the stage, and we've officially lost our chill! During the iHeartRadio Music Festival on Sept. 22, Justin Timberlake [2] surprised the crowd by bringing out Shawn Mendes for a special performance of "What Goes Around . . . Comes Around [3]," and it was just as epic as it sounds. The two showed off their swoon-worthy vocals as they crooned the lyrics to the stripped down version of the song.

Before bringing Shawn on stage, Justin couldn't help but gush about the 20-year-old saying he was "one of the coolest cats I've met." And it seems like Shawn was just as star-struck. After their duet, the singer thanked Justin on Instagram [4] writing, "Thank you @justintimberlake for being such an incredible guy." Can these two do more music together ASAP?

Justin Timberlake and Shawn Mendes duet at iHeart Radio Music Festival