Tennis

Tennis was a racquet sport played on Earth. K9 erased all his knowledge of tennis from his memory banks, when he followed Romana's instructions to "forget it" literally. (TV: The Stones of Blood) Later in the Doctor's life, Jack Harkness was seen trying on a tennis outfit complete with racquet for a tv show but did not seem to like it, claiming it was 'too safe'. (TV: Bad Wolf) Still later, the Tenth Doctor used a tennis racquet to hit General Staal's Probic vent. (TV: The Sontaran Stratagem)