Shawn Mendes Surprises Brooklyn Crowd With Ed Sheeran For 'Mercy' Duet: Watch

While Shawn Mendes was in the middle of illuminating Brooklyn's Barclays Center Wednesday night (Aug.16) during his hit "Mercy," the freshly 19-year-old singer had a little something in store for those in attendance -- in the form of a ginger-haired Englishman.

Yes, as if the screams weren't close enough to measuring on the Richter scale between Mendes and his fellow heartthrob opener Charlie Puth, Ed Sheeran made a surprise appearance. Dressed as casual as the way he made his way on stage in bright red shorts and a flannel, Sheeran completed the second verse of "Mercy" with Mendes before the two harmonized for the rest of the song (and subsequently made the sold-out arena go ballistic).

"That was just as crazy for me as it was for you guys," Mendes told fans as Sheeran waved goodbye and walked away. As one fan pointed out on Twitter, almost exactly four years ago to the day Mendes tweeted "To ever meet ed sheeran would honestly be the best, hes 100% the person i look upto for music." Talk about a full-circle moment.

Sheeran's cameo was almost so quick it didn't even give fans a chance to pick their jaws up off the floor, but it was definitely one that was special for everyone in the arena.

Watch Sheeran's pop-up performance with Mendes below.