Play-in game

A play-in game is a game at the beginning of a tournament that forces the lowest qualifiers for the tournament to play each other before the main portion of the tournament begins. This gives an added advantage to the higher qualifiers, allowing them to rest, while the lower teams extend themselves by playing. Further, teams that participate in the play-in must usually play the next game against the highest qualifier in the tournament and play on the road. Having a play-in game allows for a tournament to have a number of teams that is not a power of two, and gives an extra advantage for teams to play for, as they try to win to avoid having to play in the extra game.

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Wikipedia