Foo Fighters have a new album called Concrete And Gold coming out in a couple of months, and it’s set to feature some leftfield guests like Boyz II Men’s Shawn Stockman, the Kills’ Allison Mosshart, and the Bird And The Bee’s Inara George. Dave Grohl has always teased that the “biggest pop star in the world” is also on the album, singing backup. He won’t say who the pop star in question is, and he’s acting like it’s a big mystery. So let’s figure it out.

Last month Grohl told Radio 1’s Annie Mac that the pop star in question “sings backup on one of the heaviest songs on the record,” and he intends to keep the star’s identity a secret. Now talking to Rolling Stone he walks back the phrase “pop star,” saying that the singer is actually “more than that.” Here’s the story, as he tells it:

It was sort of towards the end of the album and this person came up and said, “Man, I’d really love to sing on your record.” I looked at [producer] Greg [Kurstin] and said, “OK, come in tomorrow and we’ll figure something out.” So we found a backup part for this person to sing and we decided we were gonna make it our own dirty little secret and see if anyone can figure it out…

I’d be amazed if anyone can really figure it out. But it was great and this person’s been around a long time. And I think I’ve met this person maybe a few times, but I’d never spent time with this person, and we had a blast together. Really fucking fun. And [he or she is] very talented — more so than I ever knew. But, of course, I fucking ran my mouth off; now I have to answer to it every time I pick up the telephone and I’m like, “Fuck! I shouldn’t have said anything.”

He also clarifies that it’s not Adele or Taylor Swift. And let’s go ahead and say that it’s not Drake because there’s no way that it’s fucking Drake. Grohl also says that the singer might be be on the next season of his HBO show Sonic Highways. And he mentions recording in the same studio as Justin Timberlake, Lady Gaga, Deep Purple, and Rufus Wainwright, though he won’t say if the singer in question is one of those.

So it’s obviously Lady Gaga, right? She’s a big pop star, old rock guys love her, she loves old rock guys, and she was already in the studio in the first place. Dave Grohl is bad at mysteries.