Being Assertive

It is not often that I get the chance to be assertive and do what's best for myself. Usually I'm sort of a pushover, but today I actually stood up for myself............
On the tennis court with a new partner. We get ready and she says to me, "Move up 2 steps". I say no and she says "Do it". I say no again and explain to her that I am not moving, this is where I stand and where I am comfortable. She keeps saying "move" and I finally tell her that I am not moving and to stop telling me what to do.
A couple of more times during the match she tells me what to do and I basically ignore her. We go on to win the match.
There is a way to give people advice and being rude and condescending is not one of them. I invite everybody to grab some assertiveness and use it when needed.