Snooker results: Mark Allen edges out Mark Williams to set up Northern Ireland Open semi-final with Neil Robertson

The home favourite, who won this title in emotional circumstances 12 months ago with a 9-8 victory over John Higgins, delighted the Waterfront Hall crowd once again by coming through a hard-fought encounter 5-4.

Allen trailed 2-0 early on as the Welsh legend compiled breaks of 62 and 70 but he hit back with runs of 77 and 74 in the next two frames to level matters.

Neither player managed a single break over 50 in the remaining five frames but despite seeing a 4-2 lead wiped out by Williams, the Northern Irishman scrapped over the line in a decider.

Robertson had earlier claimed his sixth consecutive win over Mark Selby thanks to a 5-2 triumph.

The Thunder from Down Under is looking to achieve a career Home Nations slam this week having previously won the Welsh Open (2007 & 2019), Scottish Open (2017) and the English Open (2021) while Selby's hopes of lifting the Alex Higgins Trophy for the first time are over.

Robertson took the opening frame with a break of 73 only for the Leicester cueman bounce back in a scrappy second before taking the second with a fine run of 95.

The 40-year-old Aussie responded with a break of 97 to restore parity at the mid-session interval and won the next three after it with breaks of 84, 63 and 73 to seal his place in the last four.

Robertson told World Snooker: "I thought it was really good. Certainly my best performance of the week. Every time I seemed to go for a long ball they went in and I scored very heavily from it as well. There are a few matches against Mark in the last couple of years where I’ve won deciders. They are a toss of a coin that could go either way. It isn’t like I’ve got the wood on him, but it is a great record to have. He is a wonderful player.

"It is an extra incentive this week to try to win as nobody has won all four Home Nations before. It is a nice thing to try and do. I am very motivated coming here anyway because I haven’t got the best record in this event. It is great to get down to the one table set up and I’m sure it will be an amazing crowd at the weekend."

Earlier, Zhou Yuelong won the final three frames of the match to beat David Gilbert 5-4 and reach the semi-finals.

Twice a ranking finalist, Zhou is one win away from a third go after an unlikely turnaround which had much to do with Gilbert, who missed two simple blacks off the spot with the winning line in sight.

The first, at 4-3 ahead, saw Zhou step in and force a decider and the very same thing happened in the final frame, Gilbert missing a huge chance which allowed the Chinese youngster to fire in a fabulous 130 clearance.

It was undeniably an opportunity missed for Gilbert, but Zhou was superb in making the most of his opportunities. He'll face either Lyu Haotian or Anthony Gilbert next.

"Do you know, at 4-2 down I felt 'I can win'. I don't know why," said Zhou. Asked why, he said: "I don't know!"

Asked about a potential meeting with Lyu, he added: "We played the Youth Championship together. I hope we can share the semi-final table, so one Chinese can get in the final."