record was 6 hours and 33 minutes and they were two hours away from doubling the old record from endurance is the explanation for this even matching or similar styles of play? because the question i keep getting asked is, why did this happen, not how did they survive it so much? they're athletes. but why? >> yeah, that is the right question. i think it is a little bit the styles. two really good servers. for sure john isner is the best in the game, and two guys who can't really return that great. so the challenge of trying to win four straight points on the other guy's serve just seemed something they weren't able to achieve. and it really is this extraordinary combination of events that made this result happen. >> the best match i ever covered was ross co tanner over born boring in '79. it took three hours. and it was -- one long grunting sweat. the conners match in 1991 was forever. many of the mcenroe matches were long endurance battles.