The U.S. team beat Japan on Tuesday night and Puerto Rico won its game with the Netherlands. Seattle Mariners pitcher Edwin Diaz, who threw two innings that led to a winning game, will be allowed to pitch an inning in the final game.
For the U.S., getting to the finals is a first; the team had only reached the semi-finals once, in 2009.
The World Baseball Classic was last played in 2013. The defending champions were the Dominican Republic and Puerto Rico had made it to the semi-finals.