Rankings
ATP publishes weekly rankings of professional players, ATP Entry Ranking, a 52-week rolling ranking and until 2009, the ATP Race, a year to date ranking. The Entry Ranking is used for determining qualification for entry and seeding in all tournaments for both singles and doubles. Within the Entry Ranking period consisting of the past 52 weeks, points are accumulated, with the exception of those for the Tennis Masters Cup, whose points are dropped following the last ATP event of the year. The player with the most points by season's end is the World Number 1 of the year. At the start of the 2009 season, all accumulated ranking points have been doubled to bring them in line with the new tournament ranking system.
ATP Race was an annual race from season start to season end but was discontinued beginning in 2009. Every player would start collecting points from the beginning of the season. At the end of the season, the ATP Race determined which players and teams (first eight for singles and first four for doubles) can compete in the Tennis Masters Cup, now called the World Tour Finals.
Read more about this topic: Association Of Tennis Professionals