There have been a number of noteworthy rivalries. Here is a listing of some of the greatest rivalries. 
For the purpose of this essay only, the standards for inclusion are (all must be met):
Both players have to have a career high ranking of world No. 3 or greater, and at least one of them must have reached No. 1.
Both have to have met numerous times in semi-final or final phases of Grand Slam events (or Pro Slam and also WCCC and WHCC count).
At least twelve of the career match-ups involving them must be in main (regular) tour or circuit series of championships.
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