The United States and Japan face off again in the Women's World Cup final on Sunday, and their game can't end in a tie.
Group stage games are allowed to end in ties, but from the Round of 16 onwards, all matches must have a winner. That means the USWNT and Japan will have to play extra time, then go to penalties if the score of the final is tied after 90 minutes on Sunday.
If a match ends tied after 90 minutes, there are 30 minutes of extra time, separated into two 15-minute periods. One period will be played, then there will be a break, then the other period is played. Stoppage time is added on just like it is during the first and second halves.
The entire 30 minutes has to be played in its entirety -- there is no "golden goal" rule in effect. If one team scores, the other team will have an opportunity to equalize and force penalties.
Penalty kicks are best of five, with sudden death afterwards if the teams are tied. PKs end when one team is mathematically unable to win the best of five. For example, if one team scores their first three spot kicks and the other team misses their first three, the match is over before each team takes five penalties, because the trailing team cannot come back. Sudden death features each team taking penalties until one team misses and another scores in the same round.