|Venue: Crucible Theatre, Sheffield Dates: 16 April-2 May|
|Coverage: Watch live on BBC TV and Red Button with uninterrupted coverage on BBC iPlayer, the BBC Sport website and the BBC Sport app|
Mark Williams produced a scintillating potting display to battle back to 13-11 down in his World Championship semi-final against Judd Trump.
The three-time champion trailed 7-1 overnight and fell 12-5 behind when Trump opened the third session with a superb 120 break.
But Williams made four half-centuries and a sublime 137 break to win five frames on the spin.
And while Trump then had a run of 113, Williams took a tense final frame.
Their match is set to play to its conclusion on Saturday from 14:30 BST.
Earlier on Friday, world number one Ronnie O’Sullivan moved into a 10-6 lead over John Higgins as he took control of their last-four meeting.
Resuming at 4-4, the six-time champion was always more fluent, making five half-centuries to gain a 9-6 advantage. Higgins was guilty of a series of loose shots and of failing to score heavily from several good chances.
And his misery was compounded when he missed a black off the spot and then saw O’Sullivan take the frame to a re-spotted black before winning his fifth in a row.
Williams makes remarkable recovery
Having apologised on Twitter for his performance in the first session, Williams – in his seventh world semi-final – was much improved on Friday morning as he shared eight frames with Trump.
But the Welshman began the evening shaking his head and ruefully looking up into the Crucible crowd as he left a red over the left corner, with 2019 winner Trump duly potting it on the way to a sensational start.
Williams’ response was immediate and emphatic as he constructed his 14th century of the tournament and made two half-centuries in the following frame to transform the feel of the match.
Trump, who has won 23 ranking titles and has a superior head-to-head record against the Welshman, had come into Friday evening’s session capable of winning the match with a session to spare.
But instead of it being a processional run towards victory, he was consigned to his seat for long periods as Williams rattled in a series of stunning long pots to huge roars inside the arena.
Breaks of 57 and 77 brought Williams to within two frames of Trump at 12-10, with the Englishman failing to pot a ball for more than 30 minutes.
Trump briefly stemmed the tide with a wonderful break of 113 but with Williams winning the final frame of the evening, it raises the prospect of the 47-year-old completing the largest-ever Crucible semi-final comeback on Saturday.
‘Williams and Trump is back on’ – analysis
1997 world champion Ken Doherty on BBC Four
What a performance. The match between Judd Trump and Mark Williams is back on.
Mark has something that is innate in all great champions. He believed in his technique and composure and showed a lot of character. He [Mark Williams] is one of the greatest players that has ever played this game. He did not want to give it to Judd easily and he potted some great balls.
O’Sullivan pulls clear
O’Sullivan, who is hoping to equal Stephen Hendry’s record in the modern era of seven Crucible titles, had run through the gears during the later parts of the first session with two tons and three half-centuries.
For most of Friday afternoon, he was able to pick up where he had left off, although he was aided significantly by four-time winner Higgins.
The Scot’s woes began when he inadvertently knocked a red into the bottom left corner after potting the brown to allow O’Sullivan to make a clearance of 73.
Higgins suffered more misfortune in the 10th frame, potting the black but seeing the cue ball flick off the green into the left middle pocket.
However, when O’Sullivan missed a difficult long red, he levelled the match and the pair traded frames to go into the mid-session interval at 6-6.
From there O’Sullivan cut loose, with runs of 91, 55 and 70 to add to an earlier 99, while Higgins continuously broke down among the balls and missed a routine black in the final frame of the session which would have limited the damage.
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