Carter clinched victory in a match that went down to the wire
Ali Carter clinched a place in the semi-finals of the UK Championship after winning the final frame of his quarter-final match with Mark Williams.
Williams had a chance to set up victory but got a bad contact when he tried to pot an easy red and Carter went on to clear the table and snatch a 9-8 win.
Marco Fu also made it through to the last four after he beat Joe Perry 9-7.
The result gave Hong Kong's Fu revenge for his defeat at the hands of Perry in the second round last year.
The pair were locked at 4-4 after the first session but Fu made four half-century breaks in five frames after the interval to pull ahead.
But with Fu one frame away from victory at 8-5, the momentum of the match swung back Perry's way as he closed to 8-7 with breaks of 84 and 53.
Fu, though, sealed victory with a break of 81 to finally extinguish Perry's challenge and set up a meeting with Carter on Friday.
Williams will be left to reflect on what might have been, after he claimed the opening three frames - the highlight being a 136 break in the second.
"Yeah, I could have won," said Williams.
"It was a thunderous kick in that final frame and that cost me the match in the end but I had more than enough chances to win the game before then.
"I had my chances, I blew it really so I can't grumble too much."
The Welshman showed flashes of vintage Williams as the experienced left-hander rolled back the years to show the same sort of quality that won him two World Championships.
"Most of the matches here, until this session, I have played quite well," former world number one Williams told BBC Sport.
"But in this final session, I played like a bulldog chewing on a wasp.
"I had plenty of chances and there was a lot of pressure and I didn't handle it very well.
But Carter, who memorably gave up an 8-3 lead to Barry Hawkins to lose in the opening round of this event last year, showed resolve to claw the game back to 5-3 heading into the evening session.
The pair exchanged frames immediately after the resumption before Carter again clawed his way back to level the match at 6-6.
Williams responded with a break of 66, without reply, in the next frame but Carter refused to be shaken off easily and took the match into a decisive frame.
Williams had looked likely to clinch his place in the semi-finals when Carter fouled on the pink to give his opponent a 29-0 lead and a seemingly simple pot on the red with the balls spread.
But the former world champion got a kick and saw the red bounce out of a middle pocket, allowing Carter his chance.
"Hopefully the consistency will come," said Williams.
"Out of all the sessions, I only had one bad session.
"It is sickening to go out like that because I had him, I was 30 up and snookered him. I could have put them back but the red was easy and I was never going to miss it until the kick."
In Thursday's two remaining quarter-finals, Scottish pair Stephen Maguire and John Higgins face each other and Shaun Murphy will play Stephen Lee.