How do I create a custom game with spectators?

is it possible to create a custom multiplayer game that has spectators? I would mainly like to run a 1v1 against AI and have human spectators look at it. Is this possible, and if so, how? General info on spectators is also wellcome.

Solution 1:

Create the the custom game, ensure the game mode is set to 1v1, add the AI opponent who will join team 2, and finally, click +Player to invite your friends to spectate.

You can right click on players in the game lobby and force them to spectate or nominate them as a referee. Referees are spectators with the ability to chat with players.