Novak Djokovic clawed his way to a two sets to one lead over great rival Rafael Nadal before their scintillating Wimbledon semi-final was paused on a knife-edge.
With the clock slipping past 11pm (local time) - the official curfew for action at the All England Club - Djokovic survived two set points in a gripping tiebreak to edge ahead.
Battle will resume on Saturday with the Serb leading 6-4 3-6 7-6(9) and needing one more set to book a Sunday showdown with South African eighth seed Kevin Anderson.
Anderson earlier won the longest-ever Wimbledon semi-final in a test of endurance with American John Isner that finished 26-24 in the fifth set after six hours and 36 minutes.
Anderson and Isner are pleading for officials to introduce deciding tiebreakers after engaging in the longest grand slam semi-final in history.
"I don't really know what to say right now," Anderson said.
"Just playing like that in those conditions, it was really tough for both of us.
"John's such a great guy and I really feel for him because, if I'd been on the opposite side, I don't know if I could take that, playing for so long and coming up short.
"You feel like this is a draw for the two of us but somebody has to win.
"So I apologise if I'm not more excited right now because the mix of emotions getting through something like that is quite different."
The last set alone lasted five minutes shy of three hours and Anderson said it was unfair on both players.
"I really hope we can look at this and address this because in the end you don't even feel that great out there," the eighth seed said.
The US Open is the only grand slam to use tiebreakers in the fifth set, with the Australian Open and French Open, like Wimbledon, both playing advantage sets.
Isner said he agreed with Anderson that tiebreakers - at some point in the fifth set - were the way to go.
"If one person can't finish the other off before 12-all then do a tiebreaker there," the ninth seed said.
"I think it's long overdue."