Barrowman teamed up with Victor Garber and Jesse L. Martin to sing More I Cannot Wish You in the 60-minute musical superhero spectacular, and boy did he give it his all.
John was due to begin his eight-date "Fabulous Christmas Tour" at the Bristol Hippodrome on Saturday.
But in a tweet he said he had been rushed to hospital with a neck injury that made it "impossible to sing and move".