Shawn Mendes joins John Mayer onstage in Canada

Teenage pop star Shawn Mendes surprised fans in his native Toronto, Canada on Monday (03Apr17) by joining rocker John Mayer onstage for his latest tour stop.

The Daughters singer recently hit the road for his Search For Everything world tour, and he invited a very famous local to share the spotlight with him in Toronto.

Shawn teamed up with John to perform a special mash-up of his track Mercy and John's In Your Atmosphere, strumming their acoustic guitars as they traded verses, much to the delight of the audience.

After the gig, the 18-year-old, who has always cited John as one of his career inspirations, took to Twitter to gush about the collaboration.

"Damn," he wrote. "John Mayer is the best. My job is the best. U guys are the best. What an insane night."

The feeling was mutual as Mayer, 39, took to his Instagram page to post a photo of the two musicians onstage.

"The dynamite @shawnmendes joined me in Toronto tonight perform a Mercy/In Your Atmosphere mashup and it was over the top good," he captioned the snap.