Place the jacket on a flat surface if available. Spreading the jacket out will make it easier to work with.
Fold the collar and lapels upward. Fold each jacket sleeve inside the shoulders so that they will be held secure and not hang loosely, which will limit wrinkling.
Fold the edges of the jacket together so that they meet in the center. This will serve to make the jacket smaller so it will fit into your suitcase more easily.
Fold the jacket in 2 at the center seams so that the 2 halves meet in the middle. This will help keep the jacket flat during travel.
Fold the jacket in half again so that the buttons and collar meet. Your sports jacket is now reduced in packing size and ready to be placed in your suitcase.