Network multiplayer game - server and client at the same time

Hi, I'm making a multiplayer online game where a player can create a battle(acting like server) and another player can join the battle(acting like a client), i'm using the unity masterserver for that. Every player has to login and connects to a server when the game starts, so I can have a list of everybody who are connected at the moment (this way I make a chat with everybody for example). The problem is if a player create a battle he will become a server, but he was already connected to the initial server, he would have to be client and server at the same time? Is there a way he can create a battle without lose the connection with the server that he connected when he made the login?

thanks