Shawn Mendes has uploaded footage of himself performing his song 'Mercy' with Niall Horan backstage at the American Music Awards, which were held on Sunday (November 20).

Mendes commented on the Instagram video that Horan is a "lad", with the clip viewed nearly one million times on Monday (November 21) despite it only being uploaded just hours before.

Both acts performed on the night, with Horan running through his debut solo single 'This Town' as he continues life without One Direction. Mendes was nominated for the new artist of the year category, but the award went to Zayn.

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Watch the duet video below: