World TeamTennis is a coed professional tennis league played with a team format in the United States which was founded in 1973.Originally played on a no-line court, each match consists of five sets. Each set features a different configuration (men's singles, men's doubles, women's singles, women's doubles, and mixed doubles). Prior to each match, coaches decide the order in which the sets will be played. Each player on a team usually plays in at least one of the five sets.