Surely none of their 43 previous encounters has been invested with the tension, significance and, ultimately, the pathos that Rafael Nadal and Novak Djokovic brought to Court Philippe Chatrier on the 11th day of the 2015 French Open.
In three sets of steadily mounting pain, the Serb won the 44th battle, his first over the Spaniard in six attempts here, the sixth of their past seven encounters, and advances to the semi-final on Friday.
It was not a contest just about the past, though; it was about the future too – more so, in fact.