Ed Sheeran surprises fans at Shawn Mendes gig

Ed Sheeran gave fellow pop star Shawn Mendes a big boost on Wednesday night (16Aug17) by joining the teen onstage for a show in New York.

Shawn was headlining a gig at the Barclays Center in Brooklyn, where he treated fans to a brief cover of Ed's track Castle on the Hill, before playing his own ballads Life of the Party, Three Empty Words, and Roses.

However, the Castle on the Hill rendition turned out to be a teaser for an even bigger surprise the singer had in store for attendees later on in his set - an unexpected appearance from Ed himself.

Devotees were sent into a screaming frenzy as the British superstar stepped out onstage to perform with Shawn, teaming up for the second verse of the 19-year-old's track Mercy, with both musicians strumming acoustic guitars.

After the short duet, Ed headed backstage, as Shawn gushed to the crowd, "That was just as crazy for me as it was for you guys!"

He later shared a photo of the pair in action on Instagram, and expressed his gratitude to Sheeran by captioning it, "Thank you !!!"

The collaboration was all the more special for Shawn as it had taken place in the Big Apple, a city of particular significance for the youngster.

"I just want to say that there are these very certain cities in the world that make me go crazy before I get on stage, and this is one of them," he told the Brooklyn audience earlier on in the concert. "I always have to mention it that the people who found me in the very beginning of my career are here tonight, the first fans who stopped me on the street to take photos. You guys had no idea this was happening, and now it's happening. It's incredible, so enjoy the show."

The gig, which also featured Charlie Puth as the show opener, was part of Shawn's Illunimate World Tour, which kicked off in the U.K. in April (17) and ends in Japan in December (17).