One-quarter and one-half Basketball and gridiron football are two-half games that may be further broken into two quarters. In the case of a tie at the end of the fourth quarter, a fifth overtime "quarter" may be played. This happens only if there is still no winner after four overtimes. A third way to resolve a game with ties is through a "Shootout". Each team has three chances to shoot free throws in succession without fail to win. If the first two shots go nowhere, then the third try wins the game. In Rugby Union, the term "quarter" refers to each period of play of 10 minutes duration. A half is equivalent to 20 minutes of playing time. In American Football, the term "quarter" refers to each play during a single offensive or defensive series, which is five minutes long. In Soccer, the term "quarter" refers to each side's opportunity to score goals during their half of the field. There are 15 minutes left on the clock when the first half ends. Should there be a goal before the end of the half, then the referee will whistle for the start of the second half. No extra time is needed in soccer to determine a winner because there will never be a need for more than one half of play. In Tennis, there are also periods of play of 10 minutes duration, called "quarters".