Sydney Sweeney Poses Nude on W Magazine Cover

Sydney Sweeney let it all hang out for W Magazine ... she posed nude for a photo shoot dedicated to the year's best performances.

Check out the insanely sexy pics ... Sydney went Old Hollywood glam for the shots, where she wears nothing but a curled coif and a diamond necklace.

In one shot, the photo seems to be rotated on its side, giving the "Anyone But You" star the appearance of floating in mid-air. Her right hand cups her bare breast as she alluringly stares down the camera.

In another, Sydney shoots an over-the-shoulder come-hither look in a dark room where she finds the only light to show off her curves.

The pics are a far cry from the role of the real-life boxer she plays in "Christy." And growing up, she may have been closer to Christy Martin than Marilyn Monroe. She admitted to W she's racked up a few battle scars in her time.

She said ... “I have a scar next to my eye. I got it when I was 10. I was wakeboarding, and I jumped the wake, and I tried to do a 360, but the tip of my board came up and sliced me in the face. I had to get, like, 17 stitches."

She also recalled ... "I tore my MCL dirt-bike riding, and the scar just never went away. Then I have a keloid scar. I got bit in Australia when I was filming the movie 'Eden,' and I don't know what I got bit by. It just turned into this crazy crater; then it scarred.”