"Law 14: The follow-on". In a two innings match, if the side batting second scores substantially fewer runs than the side which batted first, then the side that batted first can require their opponents to bat again immediately. The side that enforced the follow-on has the chance to win without batting again. For a game of five or more days, the side batting first must be at least 200 runs ahead to enforce the follow-on; for a three- or four-day game, 150 runs; for a two-day game, 100 runs; for a one-day game, 75 runs. The length of the game is determined by the number of scheduled days play left when the game actually begins.