move in on (someone or something)

1. To advance on someone's or something's position, especially so as to capture or attack them or it. Police officers began moving in on the suspect's location. The pack of wolves moved in on the injured deer.

2. To advance on someone or something in order to exert control over or derive some benefit from them or it, usually when doing so is unwelcome. Are you trying to move in on my girlfriend? Why are you always flirting with her? I just hope that new shop doesn't move in on our business.