That year, 96 men and 63 women entered, and prize money totaled $100,000. In 1970, the US Open became the first Grand Slam tournament to use a tiebreaker to decide a set that reached a 6–6 score in games. From 1970 through 1974, the US Open used a best-of-nine-point sudden-death tiebreaker before moving to the International Tennis Federation's (ITF) best-of-twelve points system.[1] In 1973, the US Open became the first Grand Slam tournament to award equal prize money to men and women, with that year's singles champions, John Newcombe and Margaret Court, receiving $25,000 each.[4] From 1975, following complaints about the surface and its impact on the ball's bounce, the tournament played on clay courts instead of grass.