Queen guitarist Brian May has recalled how the band may have had to break up had their album A Night At The Opera not been a success.
The album, the band's fourth, was released in 1975 and featured tracks including Bohemian Rhapsody and You're My Best Friend, written by bassist John Deacon.
May, 73, was speaking as part of the Queen The Greatest series currently featuring on the band's official YouTube page.
In a video clip, May says: "We were not only poor, but we were in debt. All the sound and lighting companies and the people that we worked with hadn't been paid. So we were at a really crucial point. We might have had to break up if that album hadn't done well."
The YouTube series is celebrating key moments in the band's history with weekly instalments.
In the fifth episode titled Queen: 1975 A Night At The Opera - Make Or Break, May says: "It was an expensive album, enormous complexity on there. Even looking at it now I wonder how we did some of that stuff."
Queen drummer Roger Taylor says: "I remember when we went into the studio to make A Night At The Opera, it felt like make or break".
The album, named after the Marx Brothers film, is regarded as one of the best albums in their catalogue, with classic tracks including Freddie Mercury's Love Of My Life and Taylor's I'm In Love With My Car.
At the time of its release, the album was reportedly regarded as one of the most expensive produced in the UK.
In 2018 the album was inducted into the Grammy Hall Of Fame.
Episodes of Queen The Greatest can be found on the band's official YouTube page.