have the drop on (someone or something)
To have an advantage over another person; to catch someone else in a vulnerable position or situation. I think we'll have the drop on the defense if we run this play next. The police received an anonymous tip and had the drop on the would-be robbers when they entered the bank.
have the drop on
have the advantage over. informal Have the drop on was originally a mid 19th-century US expression used literally to mean that you have the opportunity to shoot before your opponent can use their weapon.
2000 Clay Shooting He always seems to have the drop on me by one bird no matter how hard I try.