Since 1887, the winner of the next game at five-games–all took the set in every match except the All-Comers final and the challenge round, which was won by the player who had won at least six games and at least two games more than his opponent. This advantage format was introduced for the final sets of early rounds, for women starting in 1887, and used for all sets in final rounds from 1887 through 1969. The tie-break system was introduced in 1970 for all sets, in its best-of-nine points sudden death version until 1974, and in its best-of-12 points lingering death version since 1975. The US Open is the only Grand Slam tournament to have a third set tie-break, which has occurred twice in women's singles finals in 1981 and in 1985.