Another track has leaked from John Mayer’s forthcoming album Battle Studies, prior to its Nov. 17 release date: “Half of My Heart,” a duet with country starlet Taylor Swift.

The “Love Story” singer is a big fan of the rocker but never dreamed she’d get to sing one of his songs.

“I was so excited when he Twitter-messaged me. He was like, ‘Hey, I just wrote this song this morning and I can only hear you singing on it with me. I was like, ‘Yes!’”