Mark Williams held off a superb fightback from fellow former winner John Higgins to triumph in a last-frame decider and reach his eighth World Championship semi-final at the Crucible.
The veteran duo, who have won seven world titles between them, were locked at 8-8 at the end of their second session before Williams put himself on the brink by taking all four frames on Wednesday's resumption.
Four-time champion Higgins, though, dug in following the mid-session interval with breaks of 94, 114 and 67 to force a decider, which Williams took after his opponent missed a tense blue on the top cushion to seal a 13-12 victory.
Williams, who had trailed 5-1 earlier in the match, made the most of some unforced errors from Higgins, 49, to edge in front and then extend his lead to 10-8.
A couple of half-century breaks from the Welshman, who claimed the last of his three world titles in 2018, saw him seemingly close in on victory at 12-8 heading into the interval.
However, having regrouped, Higgins clawed a frame back before firing in 94 to move within two.
Williams, 50, then gave away a careless foul after touching the blue with his trailing arm when he was leaning over to pot a long red with the rest.
Higgins made the most of the opportunity, digging in again to build a fine 114 break.
The Scot missed a frame-ball red along the bottom cushion after a break of 67 in the next but was still able to force a final-frame shoot-out.
With both men running out of position when looking set, the deciding frame turned into a safety battle before Higgins caught the bump on the middle pocket, which allowed Williams in to edge in front 56-52.
Higgins sunk a red with the rest after Williams missed a tricky long red, then rolled the brown in on the top cushion only to miss the blue.
Williams clipped it in before finishing off the pink and black to seal a dramatic 74-69 victory.
Ronnie O'Sullivan held off a fightback from Si Jiahui to lead 10-6 heading into Wednesday night's final session.
O'Sullivan extended his overnight advantage to 7-2 when he took the opening frame of the morning, capitalising after Si had missed a straightforward pink off the spot.
Si, a semi-finalist on his Crucible debut two years ago, then crafted a break of 101 before a fluked cannon red into the bottom corner helped set O'Sullivan on his way to a run of 75 to take the 11th frame in one visit.
Si reduced the deficit again heading into the mid-session interval, but O'Sullivan pinched the first frame back after his opponent missed a frame-ball red, getting a couple of snookers before clearing the colours.
Si rattled off consecutive half-centuries to get back to 9-6, but O'Sullivan capitalised on another unforced error from Si when missing the brown to come from behind and take the final frame of the session with a 64 break.
Zhao Xintong duly picked up the one frame he required to turn a 12-4 overnight advantage over Chris Wakelin into a 13-5 victory that sealed his place in the semi-finals for the first time.
Thursday May 1
Schedule TBC
Friday May 2
Schedule TBC
Saturday May 3
Schedule TBC
Sunday May 4
13:00-18:00
19:00-22:00
Monday May 5
13:00-16:00
19:00-22:00
