Selena Gomez has warned Justin Bieber to stay away from Miley Cyrus.

Miley, 20, and The Hunger Games actor Liam Hemsworth recently called off their engagement and Selena, 20, is reportedly worried her on/off boyfriend Justin will try to hook up with Miley, who he reportedly had a fling with a few years ago.

"Justin and Miley hooked up a few years ago. Then he started dating Selena. It created this whole jealously thing between them. Now Selena doesn't want Justin anywhere near Miley -- and they've been fighting about it!" a source said.