McFly's Tom Fletcher has tested positive for COVID-19, less than 24 hours after kicking off Strictly Come Dancing's live show.
Fletcher, as well as his Strictly dance partner Amy Dowden, tested positive for coronavirus on Sunday afternoon, the BBC said.
It said in a statement: "The pair are now self-isolating separately following the latest government guidelines.
"While they will both miss Saturday's live show, Strictly Come Dancing protocols mean that, all being well, they will return the following week.
"Strictly has and will continue to follow government guidelines in order to keep everyone safe."
The pair will not be allowed to rehearse for 10 days, as per the guidance, meaning they will miss next week's live show.
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Fletcher also missed the McFly gig in Glasgow on Sunday evening, leaving his bandmates to perform without him.
Writing on social media, he said he was "so, so sorry" to miss the show at the SSE Hydro arena.
The band added: "Unfortunately Tom is unwell and won't be onstage with us tonight in Glasgow.
"He sends huge and heartfelt apologies to all the fans he won't see tonight.
"The show will still be going ahead, we're looking forward to seeing you all and need you guys to sing extra loud for us tonight."
Under show rules, the pair should be allowed to perform the following week.
Strictly is operating in a similar way to last year, with pairs being bubbled up and a limited audience in the studio.
Last year, Nicola Adams and her partner Katya Jones (who were performing as the show's first same-sex couple) were forced to leave the show early after contracting the virus.
There had been unconfirmed tabloid reports this year that three professionals had not been vaccinated – however Dowden is not one of them.
McFly is no stranger to Strictly, with Fletcher, who is married to reigning I'm A Celeb winner Giovanna, hoping to emulate the success of bandmate Harry Judd, who triumphed in the show back in 2011.