An Earth racquet sport played in an enclosed court, the subject of a hard-fought rivalry between Miles O'Brien and the younger, fitter Julian Bashir on Deep Space 9.
Racquetball is played by two opponents striking a ball against the walls of a closed court. O'Brien builds a court on the station at his own initiative, expecting to have it largely to himself.
The game features in the Deep Space Nine episode Rivals. O'Brien discovers that Bashir captained the racquetball team at Starfleet Medical Academy and is far too good for him, and he trains obsessively for a rematch. Quark, facing competition from a rival bar, promotes the match as a public event and takes bets on it.
The contest is thrown into confusion by alien gambling devices that alter the laws of probability, giving O'Brien impossible luck until the machines are destroyed.