Annie Leibovitz for Vogue

When you play the Super Bowl halftime show two times in three years, as Bruno Mars has done, you’re a pretty big deal! But Adele thinks the “Uptown Funk!” star will be even bigger someday.

In a new Vogue cover story, Adele discusses Mars, with whom she collaborated on her 25 track “All I Ask.” The song took a mere 48 hours to finish, and Adele was blown away by Mars’ artistry during the process.

“I’ve always been a really big fan of Bruno,” says Adele, “but when we worked together he was beyond. He can do anything, literally singing the best vocals you’ve ever heard live in your life while he is playing a drum or a bass or doing some mad percussion riff. I think he definitely will be the biggest, biggest, biggest artist in the world.”

Adele also shares that current single “When We Were Young” is her favorite song on her blockbuster new album, and is “a bit of a letter to myself.” She also says that she’s quit smoking and has almost given up alchohol, after once drinking a bottle of wine per day.

Click here to read the full Vogue cover story. Adele will grace the GRAMMYs stage on Monday night (Feb. 15), after 21 won album of the year four years ago.