After Dave Grohl claimed that 'the biggest pop star in the world' features on the new Foo Fighters album, feverish speculation began amongst fans, who wondered who he might be talking about.

Adele seemed like a pretty safe bet, although many also pointed to Taylor Swift, who has been very quiet over the last year - what better way to announce your comeback than with a collaboration with one of the world's biggest rock bands?

However, Grohl has now poured cold water on those rumours for 'Concrete & Gold'.

He explicitly told Rolling Stone: "Neither Adele nor Taylor Swift sang on the record", but refused to say who did. However, he did reveal that a number of high-profile artists were recording at the same studio - EastWest in LA - at the same time, including Justin Timberlake, Shania Twain and Lady Gaga, and that he asked some of them to sing on the album - although again, did not name names.

The album's released on September 15th, so either way, we've got a month or so to go until we find out.