Singer has been watching Jennifer Anistons ex on DVD
The singer, 23, thinks the US rocker is a brilliant musician and really hot.
I think Im in love with John Mayer, Lily writes on her Twitter account. I watched a DVD of one of his concerts.
His guitar playing is mesmerising. Sexy.
John, 31, split from Jennifer Aniston, 40, shortly after the Oscars in February.