be one up on someone

be one up on someone

If you are one up on someone, you have an advantage over them, often because you have done something which they have not done or because you know something that they do not know. She will see this as the opportunity to be one up on you. You may only have met him once, but you're one up on the person who hasn't met him at all. Note: If you get one up on someone, you get an advantage over them. In those days, travel was about getting one up on one's neighbours.
See also: on, one, up