5 Seconds Of Summer had to perform at Capital's Jingle Bell Ball as a trio when bandmate Michael Clifford was unable to travel after losing his passport.
The Australian group, whose live album Live SOS will be released on December 15, were forced to carry on as a trio at the music event, after the guitarist was stranded in the US.
Ashton Irwin said before their performance: "It's going to be weird. We prefer always not to perform without Michael, but today we are going to and it's going to be weird."
His bandmate Luke Hemmings added: "There'll be less running around by a red-haired person. It'll be less active."
Michael later admitted his mistake, and apologised to fans on Twitter.
"Really really sorry to anyone I've let down by not being able to come. you get a free pass to call me stupid," he wrote, adding: "The guys did awesome."
Luke tweeted after the show: "Wasn't the same without Michael but we did our best, thanks jingle bell ball :-)."
Ed Sheeran and Taylor Swift brought some Christmas spirit to London, as they closed the concert at London's O2 Arena alongside Sam Smith and Jessie J on the second day of the music event, sponsored by Morrisons. Boy band Rixton and dance acts Sigma and Fuse ODG also played.
Taylor revealed she was battling illness, tweeting beforehand: "About ready to go on at @CapitalOfficial Jingle Bell Ball - the voice is feeling hella bad but I'm here and ready to PARTY/sound like a frog." She later wrote: "London, thanks for dancing with me tonight under confetti. Good night, London... Miss you already."
Take That, OneRepublic, Olly Murs, The Script, Ella Henderson, Union J and Jess Glynne performed on the first day.