High Quality Content by WIKIPEDIA articles! The 1973 Commercial Union Assurance Grand Prix was a tennis circuit administered by the International Lawn Tennis Federation (ILTF) which served as a forerunner to the current Association of Tennis Professionals (ATP) World Tour and the Women`s Tennis Association (WTA) Tour. The circuit consisted of the four modern Grand Slam tournaments and open tournaments recognised by the ILTF. This article covers all tournaments that were part of that year`s Men`s Grand Prix. The Commercial Union Assurance Masters and Davis Cup Final are included in this calendar but did not count towards the Grand Prix.