Snooker results: Mark Williams beats Ronnie O'Sullivan 6-5 in Masters quarter-final

Members of the famed Class of '92, two of snooker's greatest ever players locked horns in another eagerly-anticipated showdown, and the 2,000 spectators inside the arena did not leave disappointed as they were witness to a special match in every sense of the word.

For much of the afternoon, Williams appeared likely to rue a sloppy start that saw him fall 3-0 behind, though it must be said that O'Sullivan kept his opponent quiet with a terrific safety display that dictated much of the early exchanges.

Williams had only registered 26 points up until at that point, with breaks of 115 and 79 from O'Sullivan suggesting he was also going to dominate in the scoring department.

However, the Welshman gave himself a lifeline by winning the fourth frame with a typically pinpoint run of 55 that ensured he went into the mid-session interval with a foothold in the match.

Buoyed by getting his first frame on the board, Williams returned from the break by winning frame five with a classy hand of 83 and though O'Sullivan responded by taking the next frame, it was Williams who would finish the stronger as a pulsating conclusion was about to play out.

A trademark long red paved the way for a break of 90, and when he followed up by clearing the table for a masterful 143 in frame eight, his 3-1 deficit had quickly become 4-4.

And it was about to get even better for Williams, the first real sign of weakness coming from O'Sullivan when he couldn't kill off the ninth frame despite leading 51-1.

Ever the predator, Williams stepped in with a quite magnificent clearance of 59, pulling off outstanding pots on the last four colours. The final straight black was floated into the pocket in typical Williams style, despite the white being almost chained to the side cushion.

Leading for the first time in match, the momentum had now seemingly swung in Williams' favour, but O'Sullivan was not finished with and he sent the match into the deciding frame this bout so dearly deserved by dominating frame 10.

A now frenzied crowd very nearly blew the roof off Alexandra Palace when the two men returned from a much-needed breather, a fist bump and a nod of approval from each preceding the final act of this latest chapter in their long-held rivalry.

It was Williams who blinked first, misjudging a thin safety and allowing O'Sullivan to pot from distance, only for the seven-time Masters champion to miss the following black and bowing his head in despair.

Williams then looked on course for a relatively comfortable cruise to the winning line, but he was left snookered on his desired red when not opening up the pack as intended, and it was he who was now left wondering if his chance had gone.

It hadn't, and a couple of nerveless long pots under pressure left him in prime position, with the century that followed allowing him a victory lap that has been a long time coming after so many recent reverses to O'Sullivan.

A relieved Williams said afterwards: "I was 3-0 down, it was flawless stuff he played – he tied me up in knots. It was just perfect snooker.

"I made a great 50-odd to win the fourth frame and it just kept me in it.

"It's electric, it always is when you play Ronnie in London. For the first time ever, towards the end, the crowd swayed in my favour.

"He played fantastic in the first first session, but I came back well and put pressure on him. I thought 'come on, you've got a chance here'. I made a cracking 70 to finish it off.

"I know it sounds strange but I fancied beating him today. I know I'm hitting the ball well, I have been for a while and I did again this afternoon."

Lisowski beats Vafaei to reach semi-final

Jack Lisowski was victorious in the later quarter-final on Thursday, beating Hossein Vafaei 6-4 in an entertaining game.

It is just the second Triple Crown semi-final reached for Lisowski, who had never won a match in the Masters prior to this week.

The pair were locked together at 4-4, but Lisowski won the ninth frame to edge closer to victory before taking the match with an impressive 74 break.

Lisowski will now meet Mark Williams in a Saturday semi-final.