The Showdown remains Staged at that Battlefield as long as it is Contested and has units present controlled by the player that applied Contested.
§ 323.8.a Core Rules PDF (officieel)
§ 323 When a Cleanup occurs, the following Tasks become Outstanding in the order described:
§ 323.8 6. Mark a Showdown as Staged at each Battlefield that Contested was applied to.
