In the first post-season alteration in 17 years, each league will have two wild-card playoff teams instead of one. Those two teams will meet in a one-game showdown.
For one season only, the winner of the wild-card playoff game will then host the first two games of the best-of-five division-round series.
The 2-3 format was put in place for 2012 because the regular-season schedule had already been announced prior to the decision to expand the playoffs, and it was too late to include an extra travel day before the start of the post-season.
The traditional 2-2-1 format will return next year.
Players agreed to the playoff change in the most recent collective bargaining agreement, which was signed in November.
If the season had ended Thursday, the National League wild-card teams would have been Atlanta and the New York Mets. In the American League, they would have been Tampa Bay and Oakland.