In the NBA it is impossible to be reduced to fewer than five players. Instead, if a player fouls out and the team has no substitutes, the player stays in the game and his team is assessed a technical foul. The NCAA rulebook, on the other hand, explicitly allows for as few as one player to be playing:

Section 2. The Team

Art. 1. At the start of the game, each team shall consist of five players, one of whom shall be the captain.

Art. 2. Each team may continue to play with fewer than five players when all other squad members are not eligible or able to play.

Art. 3. When there is only one player participating for a team, that team shall forfeit unless the referee believes that both teams have an opportunity to win.


h/t @28andJefferson

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