All Tennis Players How Many Grand Slams Has John Newcombe Won? John David Newcombe AO OBE (born 23 May 1944) is an Australian former professional tennis player.John Newcombe has won 7 Grand Slams. FacebookTwitterEmail How Many Grand Slams Has Madison Keys Won? How Many Grand Slams Has Jannik Sinner Won? How Many Majors Has John Isner Won?