Explained: Serena and Venus Williams to play doubles together at the Cincinnati Open

Serena and Venus Williams are set to play doubles together at the Cincinnati Open, which begins next week

wild-card entry

A tournament spot given to a player or team without requiring qualification through ranking

doubles field

The group of pairs competing in the doubles portion of a tennis tournament

hard-court tune-up tournament

A tournament played on hard courts used as preparation before a major event like the U.S. Open

mixed doubles

A doubles tennis format where each team consists of one man and one woman