Pop superstar Shawn Mendes knows what a difference timing can make. Just a few years ago, the Toronto singer-songwriter was promoting himself by singing his songs on the Vine app, and this past Wednesday, Mendes was in Brooklyn about to have the surprise of his life, all thanks to perfect timing. Just as he reached the soaring, heartfelt surge in the chorus of his song, “Mercy,” Ed Sheeran, the mentor who motivated Shawn Mendes, made an appearance in a complete surprise alongside the headliner, and the moment and the music that followed was nothing short of magical.

Not solo for long

There are definitely some advantages to the present-day compulsion to capture absolutely every potentially priceless moment on camera.

A fan happened to be close-up and camera ready when Shawn Mendes opened with a simple and “stripped” version of his monster hit. There was only a tinkling electric piano backing the curly-haired chart-topper as he started the plaintive ballad before everything transformed to create an unforgettable performance.

As completely expected, the massive chorus of the Barclays Center audience virtually drowned out most of the headliner’s own stellar notes of “Mercy.” Shawn Mendes finds himself in the same peculiar performance situation as the Beatles once did at the height of their fan hysteria, wondering why he should sing at all if no one can hear him. Commendably, he carries on through every song on his current tour, and he has made a point of expressing gratitude to his homeland Canadian fans, even appreciating their volume, noting on Twitter, “That was unbelievably loud!” He also called the Montréal crowd “an animal” as lovingly as possible, with his thanks.

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There was nothing loud about the way Ed Sheeran made his way onstage beside Shawn Mendes without making a sound, except for his contribution to the chorus. Sheeran sang perfectly on key, but substantially below the shrieking din of ecstatic fans. Clearly delighted, but also flabbergasted, Shawn Mendes shot a beaming smile side stage to his crew and basked in the immaculate surprise of Sheeran becoming his partner for the moment.

Mendes took the vocals for a second verse, before a Sheeran-Mendes artistry matchup that will live on in music history for the adoring throng in attendance.

Canada and composing comrades

Ed Sheeran has a certain love for Canada in the first place. The “Galway Girl” songwriter surprised fan, Sydney Bourbeau, in 2016, while she was singing in an Alberta shopping mall. Sheeran heard her singing “Thinking Out Loud,” and unassumingly joined in, just to give her a thrill, much like his surprise for Shawn Mendes.

Shawn Mendes covered Ed Sheeran songs during the days of submitting songs on Vine, but the two prolific and creative composers have cultivated a genuine relationship since then. “Ed Sheeran wrote his songs, so I wanted to write my own songs,” credits Mendes. “He's a very sweet guy,” Mendes continues, describing the man he can now call a friend. “He's just so normal, and that the best part about him.”

Anyone seeing these composers in this live collaboration of “Mercy” can feel that the admiration and respect are fully mutual.