The ATP Masters Series is a series of nine tennis tournaments that are part of the ATP tour, held annually throughout the year in Europe and North America. The tournaments are mandatory for the top male players on the professional circuit. The series constitutes the most prestigious tournaments in men's tennis after the four Grand Slam,Australian open,French Open,Wimbledon,US Open events.
The series was introduced in 1990 with the inception of the ATP Tour. The events were originally known