Grand Slam Tennis Calendar. So as it turns out, the true calendar grand slam has only been achieved 12 times (if we don’t count wheelchair tennis). The calendar slam, often considered the peak of tennis triumph, signifies the zenith of success for any tennis player, which means winning all four grand slams.

A calendar slam involves a player winning all the four grand slams held in a calendar year, starting with the australian open, then french. Brisbane international presented by evie: