The 'Move' hit-makers released their second album last month and although 'Salute' features no collaborations it's received critical acclaim, and won the girl band many fans within the music industry.
21-year-old Jade Thirlwall said: ''The Backstreet Boys tweeted us about how they loved our album.''
The boy-band's AJ McLean wrote to them in June 2013 saying: ''hey girls this is aj mclean from backstreet boys and I gotta say I'm a big fan! U girls are the real deal, love the album!!!''
Jade - along with Jesy Nelson, Leigh-Anne Pinnock and Perrie Edwards - were the first girl group to ever win 'The X Factor' in the UK when they triumphed in 2011 and Jesy claims the 'I Want It That Way' singers - AJ, Howie Dorough, Nick Carter, Kevin Richardson and Brian Litrell - ''said they wanted to go on tour with us.''
Perrie also admitted that they're grateful for receiving help from another British girl-group.
She told Fault magazine's winter issue: ''The Spice Girls have been really supportive of us, which is amazing because they were the best girl band in the world and we always looked up to them when we were younger.''
Take a look back at October's inaugural event.
The film is expected to continue without Mendes' involvement.