The 30-year-old from Romford, a semi-finalist in the Travis Perkins UK Championship two months ago, is enjoying a resurgence two years after rashly threatening to quit the sport when his mother, Sandra, was jailed for life for the murder of her cousin.

“A couple of years ago my mum went inside and I was feeling pretty low, but now I’ve learned to live with it,” said King.

“I wasn’t really going to retire, it was just a tantrum. I had a think six weeks later and realised there was nothing I could do other than play snooker.

“I’ve got a wife and two kids to support so there’s no point being down. I’ve got to get on with things.”

King led Day, a 24-year-old from Bridgend, 4-3 before the only remaining Welshman in the event drew level with a run of 64.

The decider, like much of the match, was a scrappy affair but King clinched victory in three scoring visits.

Ronnie O’Sullivan had earlier kept his Welsh Open title defence on track after surviving a nail-biting finish against Australian Neil Robertson.

The current world champion knocked in three century breaks to storm into a 4-1 lead but came close to elimination before booking his semi-final place by holding his nerve in the deciding frame to win 5-4.

Robertson, a 22-year-old left-hander from Melbourne, had already knocked out Jimmy White and John Higgins on his way to the quarter-final.

He won the opening frame before O’Sullivan clicked into gear with a run of 62 followed by successive breaks of 110, 114 and 102.

It was the third time the world champion has compiled three tons in a row, equalling Stephen Hendry’s record.

But O’Sullivan, 29, could not close out the match as Robertson reduced his arrears to 4-3 and then drew level by potting a very difficult long green in the eighth with the cue ball tight on the top cushion.

Trailing 42-1 in the decider, Robertson had a chance to clear up for victory but ran out of position on the last red.

O’Sullivan played a superb shot to snooker him behind the black and when the Australian failed to escape he seized his chance to secure a place in the last four.

“My timing totally went and in the end I didn’t fancy getting on one ball to the next,” said O’Sullivan.

“I had a chance to win every frame from 4-2 and didn’t do it so that started to play on my mind.

“I missed really silly balls and my positional play was poor. I’ve been working on some technical things to get my consistency back and that might take time, because when my game went it was awful.

“It was difficult to see how I was going to get over the line but a lot of that was down to Neil because he put me under pressure, didn’t lie down and made it tough.

“All credit to him. He’s a very, very good player and definitely a future champion.”

Robertson was left to reflect on how close he had come to pulling off the greatest win of his career.

“I was really calm in the decider and thought I was a bit unlucky but Ronnie played a great shot to snooker me so there wasn’t much I could do about it,” he said.

“He played brilliantly to go 4-1 up but I stuck to my game plan and still believed I could win.”

Despite the narrow defeat, Robertson was satisfied with his week’s work and seems certain to secure a place in the top 32 at the end of the season.

“Any time you get to the quarter-finals it’s a good result and I’ve claimed a couple of great scalps,” he said.

“To have beaten Ronnie would have been the icing on the cake.

“Ronnie is the best player in the world so to almost beat him means that there’s no need to be afraid of anyone.”

O’Sullivan faces world number 43 Barry Hawkins, who beat Peter Ebdon 5-3, for a place in the final.