 Complete the following phrase:  The mens singles rules have undergone several changes since the first edition. From 1884 to 1911, the event started with a knockout phase, the All-Comers singles, whose winner faced the defending champion in a challenge round. The All-Comers winner was awarded the title six times 1888, 1893, 1898, 1901, 1904, 1907 in the absence of the previous years champion. The challenge round system was abolished with the 1912 edition. From 1908 to 1914, when the championships were held at Newport, mens singles draws had exceeded 128 players, but when the event moved to Forest Hills in 1915 entries would be submitted by clubs, thereby making the clubs weed out mediocre players. Furthermore, the entry fee would be set high enough to prevent cheapskates from entering just to get a seat at the tournament at a lower price and then defaulting. Since 1881, all matches but the All-Comers final and the challenge round were played as the best-of-three sets, before the event switched to best-of-five for all rounds in 1886. Best-two-out-of-three-sets matches were reintroduced for early rounds in 1917, from 1943 to 1945, and from 1975 to 1978. Before 1884, the winner of the next game at five-gamesall took the set in every match except the All-Comers final and the challenge round, which were won by the player who had 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 in 1884, and used for all sets in all rounds from 1887 to 