1. 1977 USO final - the match point from Vilas to beat Jimbo 6 - 0 in he final set!!!!! Huge
2. 2011 USO Semi Nope at 3-5 down in the 5th set and at match point down hit that screaming winner return off a huge Federer serve......then came back to win.
yeah, there probably should be a poll here, if there isn't already, about the single greatest shot...but then you do have to start qualifying it...important moment or final vs. just degree of difficulty of shot...dimitrov had that great volley last year...rosol had that great tweener last week, but not exactly gigantic moments in tennis history (was rosol's in dc?...forgot)