Ronnie O'Sullivan produced a rousing late rally at the end of the second session of his match with Ali Carter to set up a grandstand finish on Saturday.
It was a night to test the most patient side of O'Sullivan, who continually battled with himself and the cue ball in a ragged display.
Having begun the session trailing 3-5, the Rocket soon found himself 3-8 down and with the Crucible exit door firmly open.
However, from somewhere, the great champion that he is found an extra gear and breaks of 79 and 105 in the final two frames of the evening left Carter rattled, the crown buoyant and O'Sullivan sensing that he might just be able to pull off another great escape.
In truth, it was only a horrible kick for O'Sullivan in frame fourteen than stopped this game from being all square as he was well set on 54 before a heavy contact sent the red onto the far jaw of the corner pocket.
Carter was quickest out of the blocks in the morning session and took the opening frame before O'Sullivan levelled up with a fabulous clearance of 121 which included some stunning positional play.
In the blink of an eye the Rocket was 2-1 in front, runs of 44 and 61 seeing him over the line, but Carter hit back to make it 2-2 at the mid-session interval.
A flawless clearance of 115 saw Carter get his head in front for the first time and although the Rocket took the next with a break of 96, it was Carter who finished the session the stronger.
A break of 68 was enough to see him take the seventh frame and he held his nerve to take the next, earning a two-frame advantage which, despite O'Sullivan's late rally in the second session, he maintains heading into Saturday.
Allen finishes strongly to see off Perry
Mark Allen became the first player to book his place in the quarter-finals with a 13-8 victory over Joe Perry.
The pair resumed at 8-8 after Perry - first-round conqueror of defending champion Mark Selby - overturned a 5-3 deficit.
However, Allen took control of the contest by winning the first four frames of the evening, with breaks of 133 and 74 helping his cause, before wrapping victory up with a clearance of 122.
Hawkins and Lyu set for tense finale
Barry Hawkins and Lyu Haotian look set to play out a thrilling finish tomorrow following another absorbing session of snooker from the pair this afternoon.
As was the case yesterday, Hawkins set off like a train and had soon increased his overnight lead from 5-3 to 8-3.
However, Lyu wasn't perturbed and took the next four frames with some fine break-building before Hawkins pinched the last to cling on to his two-frame advantage.
Wilson leads Jones 5-3
In the other afternoon session, Kyren Wilson and Jamie Jones produced some high-quality snooker when their second-round match got underway.
After the first four frames were shared, Wilson edged into a 4-2 lead before Jones took the seventh.
A crucial eight frame went the way of Wilson, though, who regained his two-frame advantage before the players shook hands.
Breaks of 64, 54, 74, 83 and 64 have put Wilson in the driving seat but as Shaun Murphy can vouch for, Jones is sure to lay down a stern challenge when they resume tomorrow.