on a collision course

: an act or instance of colliding : clash

: an encounter between particles (such as atoms or molecules) resulting in exchange or transformation of energy

: the act or action of moving in a path from point to point

: the path over which something moves or extends: such as

: racecourse

: to follow close upon : pursue

: to hunt or pursue (game) with hounds

: to cause (dogs) to run (as after game)