The frontman had previously said the record features "the biggest pop star in the world"
Fans have been speculating who the guest could be. In a new interview with Rolling Stone, Grohl has ruled out two of the most popular theories.
Grohl did reveal that he socialised with a lot of artists who were recording at Los Angeles’ EastWest studios at the same time, including Lady Gaga, Justin Timberlake and Shania Twain. He asked some of those artists present to sing on the record, but, again, would not say who they were or who accepted.
The frontman previously revealed that a surprise meeting with singer Shawn Stockman lead to the ‘End Of The Road’ R&B legend adding his vocals to the record.
Speaking to BBC 6 Music about the ‘weirdest moment’ of recording the album, Grohl replied: “The guy from Boyz II Men walking through the parking lot and me saying ‘would you sing on our record?’ And he does – on the heaviest song on the entire record.”
He continued: “It sounds like Sabbath and Pink Floyd. It’s heavy. It’s the last song on the record. He built a choir – it’s like 40 vocals stacked. It’s insane.”
Foo Fighters release ‘Concrete And Gold’ on September 15, and will play a one-off UK tour date at The O2 in London on September 19.