Lady Gaga has been working in the studio with Sir Paul McCartney.

The US star revealed the news on Instagram on Tuesday night (February 4) with a few photos.

The first image sees Gaga and McCartney alongside a series of musicians, including Pearl Jam guitarist Mike McCready.

She wrote: "Had a beautiful session with Sir Paul McCartney and friends. Working on one of his many secret projects! Killer musicians, vibe, and lots of laughs."

The 'Applause' star then revealed a picture of herself and the Beatle, adding:

"Always a good time with my buddy. I'll never forget when he called me last year to work and I hung up the phone cuz I thought it was a prank!"

Gaga then added an image of sheet music set up in a studio.

McCartney meanwhile features on Rihanna's new single 'FourFiveSeconds', as well as Kanye West's 'Only One'.

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