One chasing, one running. If this occurs, just make sure the one running doesn't fight back and doesn't get hurt. If neither of these things occurs, then just watch and wait. If one gets hurt, then separate them and go slower and if one fights back, then you must prepare for a lengthier introduction period. In wild rabbits, territorial behavior includes depositing marking pellets at the boundaries of the territory, chinning, urinating, and aggressive behavior such as digging, circling, and fighting.
Wild males tend to defend larger territories while females concentrate on their nests.
In our neutered domestic companions, hormonal causes may be absent, but territorial behavior still exists. Thus, when introducing new rabbits, territory must be considered and used to your advantage. What you are trying to do is eliminate the possibility for there to develop any territorial behavior in the rabbits. So you choose introductory spaces that are as different from your bunny's territory as possible. You are also trying to mimic positive feelings in your rabbits.