The Nineties boy band were set to perform a track from their new album, A World Like this, on the Jimmy Kimmel show last night.
But the practice run ended when Kevin Richardson, who only rejoined, had a face-off with lead singer Nick Carter.
The pair locked horns in a huge row before Kevin stormed off stage.
Nick then turned on pal Brian Littrell – Kev’s cousin – who was laughing at his bandmates’ squabble.
The lads put the differences behind them after being introduced to the show’s host, Jimmy Kimmel, and managed to get through the song.
The former pin-ups, whose hits include everybody (Backstreet’s Back) and I Want It That Way, have sold more than 130 million records worldwide, making them the most successful boyband of all time.
Kevin left the group in 2006, after the Never Gone Tour, and the remaining members released two more albums before slipping into retirement.
In April last year, the group announced a reunion and Kevin rejoined.
They followed with a tour, to mark twenty years in the business, and announced plans for their eighth studio album, A World Like This.
But have they really put their differences behind them? Or does Kev still Want It his Way?
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