How many rivalries cover all the bases, with meetings at all four Slams? Sampras and Agassi met at all four. So did Lendl and McEnroe. Some others that are missing a "leg": Wilander and Lendl never met at Wimbledon. Becker and Lendl never met at RG. Rosewall and Laver never met at AO or USO. Borg and Connors never met at AO or FO. Same was true for Borg and McEnroe. Becker and Edberg never met at AO or USO. Federer and Nadal have still not met at the USO. And so on.