Complex sentence: Chris Evert and Martina Navratilova are retired professional tennis players who engaged in a fifteen-year rivalry from 1973 to 1988 in 80 matches, that is considered to be one of the greatest in tennis history and in women's sports in general.
Split into simpler sentences: Chris Evert and Martina Navratilova are retired professional tennis players who engaged in a fifteen-year rivalry from 1973 to 1988 in 80 matches. It is considered to be one of the greatest in tennis history and in women's sports in general.