play one side against the other

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 one side against the other, 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 one side against the other to get them to break up.

Common Names:

Name	Pronounced	Usage
Xavier	ZAY-vee-ər (English), ZAY-vyər (English), ig-ZAY-vee-ər (English), za-VYE (French), sha-VYER (Portuguese)	English, French, Portuguese, Catalan, Spanish (Archaic)
Melech	-	Biblical, Hebrew, Biblical Hebrew
Ruy	-	Portuguese, Spanish
Edgar	['edgə]
Calanthe	kə-LAN-thee	English (Rare)
SÉVÈRe	-	French