play both ends
play both ends against the middle
To manipulate two opposing sides of an argument, conflict, competition, etc., against one another for one's own benefit or advantage. My father and my uncle are engaged in a bitter business rivalry. If I can play both ends against the middle, I might be able to secure some sizeable investments for my own company. Janet really dislikes Mary and wants to date her boyfriend Mike, so she's been playing both ends against the middle in order to get them to break up.
play both ends (against the middle)
Fig. [for one] to scheme in a way that pits two sides against each other (for one's own gain). I told my brother that Mary doesn't like him. Then I told Mary that my brother doesn't like her. They broke up, so now I can have the car this weekend. I succeeded in playing both ends against the middle. If you try to play both ends, you're likely to get in trouble with both sides.