How are the teams balanced in a versus match with less than 8 players?

Suppose I play with 3 other friends a versus match, and would like the teams to be random.

Can I leave all characters unchosen and get a 2 v 2 match? Or the result would be random also? Perhaps all 4 survivors, or infected, or 3 v 1?

Can it be configured somehow to always balance team equally (in terms of number of players)?

From gaming Juan Manuel

• StrixVaria is correct. Playing regardless of the configuration of players in Vs, the AI will fill in blank spots. When you are in game and kill a special infected, if it comes up with "Juan Manuel killed Boomer", that Boomer was an AI boomer.

  Juan Manuel : Yes Albort, but that's not what I'm asking.

  Albort : Ah yes...I see. Now that I have re-read the question. In theory, it will split 4 people up into 2v2. Once in game, you can change it around so that it is 1v3 or 3v1, and the AI will fill in the rest........(in theory)

  Juan Manuel : What does "in theory" means? Is this what you suspect? Have you read it but not tried?

  Albort : its what i remember. but it has been a while since i last played :(
  From Albort

• From some 6-player lobby experiences, the teams have been split 3/3. I have never tried with 4-players, but I'd do one of the 4p modes instead, or Team Versus (premade groups).

  The teams are selected once you hit the go button, so if it gives you something screwed up (3v1) you can cancel searching for a server quickly and balance them out.

  From Nick T

• In my experience, it will even out the teams with the advantage going to survivors. In other words, if you have 4 players in a lobby and all go random, it will put 2 players as survivor and 2 players as infected. If you have 5 players in a lobby and all go random, it will put 3 on survivors and 2 on infected, with the next player to join filling in the vacant spot to even out the teams.

  From Hooray Im Helping