Jennifer Lopez -- Enjoy the View (PHOTO)

Jennifer Lopez showed off her gymnast-level flexibility as she performed on stage at Sunday night's American Music Awards ... sending a message to other pop stars -- bow down to this booty.

The 45 year-old singer performed Sunday with Iggy Azalea ... and even though Beyonce and Nicki Minaj have reached for the ass queen throne -- this ankle-grabbing move solidifies J.Lo's position.