It means Ronnie O’Sullivan will receive a bye through to the semi-finals.
Ali Carter has withdrawn from the 2021 Welsh Open – not long before his quarter-final encounter with Ronnie O’Sullivan was about to get under way.
The World Snooker Tour revealed his decision on Friday afternoon, citing an illness that is not COVID-related.
Carter had been on a nice run of form recently, following up his Championship League Group 6 victory last week with only his second run to the last eight in a ranking event this season.
The 41 year-old secured impressive hard-fought victories over John Higgins and Mark Allen on Thursday to reach this stage.
Ali Carter, who triumphed in the Welsh Open 12 years ago and was a runner-up the following season, was hoping to secure a place in next week’s Players Championship but will just miss out on a spot in the 16-player field.
There had been general excitement too surrounding Carter’s encounter with O’Sullivan, with the pair sharing a frosty relationship in recent times.
Instead, the world champion will move directly through to the last four at the Celtic Manor Resort as his bid for a record-equalling fifth Welsh Open title received an unexpected boost.
O’Sullivan will next face either home favourite Mark Williams or fellow Englishman Tom Ford, who contest their quarter-final later today.
The semi-finalists in the top half of the draw are already known, however, with Stephen Maguire and Jordan Brown emerging as final-frame winners.
Maguire compiled a marvellous 133 break to deny reigning champion Shaun Murphy in a high-quality 5-4 battle.
Northern Ireland’s Brown, meanwhile, booked his place in the semi-finals of a ranking event for the first time in his career with a titanic and tense triumph over Mark Selby that concluded on the final black.
Live coverage of the 2021 Welsh Open is available on BBC Wales, the BBC Red Button, Eurosport, Quest, and by various other options around the world.