The rocker joined the Shake It off hitmaker to perform the band's 2012 hit Radioactive.

Following the show, Reynolds took to to thank Swift for the invite, writing, "thanks for having me @taylorswift13 u are a gem of the rarest kind - like found in stalagmites in the earths core next to t rex bones (sic)".

Swift replied, "Thank you again @DanReynolds for coming to Detroit. You're incredible."

Reynolds wasn't the only famous face at the show - Swift's Bad Blood video co-stars Gigi Hadid and Martha Hunt also hit the stage for an impromptu model walk-off.

In a message on Twitter, the pop star added, "When two of your best friends strut the runway with you during 'Style'... @GiGiHadid @iammarthahunt".