Crucible wizard Ronnie O'Sullivan brought more toil and trouble for Mark Williams with a spellbinding display at the World Championship to lead 11-5 after Sunday's session.

O'Sullivan's young apprentice Judd Trump was also back to his magnificent best against Ali Carter as he leads 9-7 in their second-round Crucible contest.

In the evening matches, Jamie Jones is 10-6 up on Andrew Higginson, while Matthew Stevens and Barry Hawkins are tied at eight frames apiece.

But it was the three-time champion whose performance particularly caught the imagination, as the 36-year-old Chigwell cueman fired two scintillating centuries and four further hefty breaks in converting a 5-3 overnight cushion into an 11-5 lead. He needs two more frames tomorrow evening to reach the quarter-finals.

At one point, O'Sullivan had won nine in a row, going from 3-2 behind at one stage yesterday to 11-3 ahead.

It was to Williams' credit that he took the final two frames of the session, but O'Sullivan's remarkable record against the Welshman looked set to continue.

Not since the Thailand Masters in early 2002 has Williams beaten O'Sullivan, who barring any collapse will face a quarter-final against Australia's 2010 world champion Neil Robertson.

Williams knew what to expect but could do little to stop O'Sullivan pouring in the heavy breaks, and for the fourth time in seven years the man from Ebbw Vale is poised to go out at the hands of snooker's number one showman.

The pair have met in Sheffield in 2006, 2008 and 2010, with the result going O'Sullivan's way each time.

Although this was day nine of the World Championship, it contained perhaps the moment at which the tournament took off.

That came at 2.55pm, when O'Sullivan completed a tremendous 107 break in the opening frame of the afternoon session, while on the opposite side of the arena Trump sealed a run of 120.

Snooker's two biggest box-office stars united the auditorium, spectators on both sides in raptures.

The century breaks set the tone for the afternoon but perhaps also the rest of the tournament. Given they are on opposite sides of the draw, the dream ticket of a Trump-O'Sullivan final is a possibility.

Williams has never lost a Crucible match with a session to spare but at one point today it appeared that the humiliation was imminent.

O'Sullivan was terrific in each of the afternoon's opening four frames, although he often had Williams mistakes to thanks for his opportunities.

Williams missed an attempted plant to let O'Sullivan in for his opening century break.

The gap went to three frames, and it was soon four. Williams was put in deep trouble behind the brown, and played the white off the side and top cushions but the wrong side of his intended target red, missing all the balls and leaving an easy starter.

O'Sullivan had a plant red in a break of 74, and Williams could only stew in his seat.

A 51 guided O'Sullivan towards an 8-3 lead, before a 68 took him to the interval four frames from victory.

The genius was still at work when they returned, and in the space of barely 15 minutes O'Sullivan had conjured magical breaks of 128 and 93.

Thoughts must have turned to a free Monday evening. O'Sullivan had chances early in the 15th frame too, but two reds were not followed by colours and Williams seized his chance, making 86 to guarantee him another night in Sheffield.

The 37-year-old, champion at the Crucible in 2000 and 2003, then scrambled through what proved easily the scrappiest frame of the session to give himself the slightest chance heading into tomorrow.

The most recent of O'Sullivan's three world titles came in 2008, when he beat Williams 13-7 in the second round.

After thrashing Peter Ebdon in the first round, O'Sullivan said he was mentally strong, having benefited from working with sports psychiatrist Dr Steve Peters, the man who has operated successfully with many of Britain's Olympic cyclists. At the same time he expressed doubt that his game was up to scratch.

Clearly, by blazing so far ahead of world number four Williams, there is little for O'Sullivan to worry about on the form score.

For the first time this tournament, Trump also looked a viable trophy contender as he came from 5-3 behind to build a 9-7 lead over Carter.

Trump was badly troubled by food poisoning as he beat Dominic Dale in round one, and the performance was again lacklustre last night as the 22-year-old fell behind to Carter, but to win six frames from eight today was impressive work.

The revival began with a quickfire run to 120 in today's opening frame, and Trump, last year's runner-up, will return tomorrow afternoon looking to complete a job two-thirds done.

Jamie Jones, the 24-year-old qualifier from near Neath, was faring better than countryman Williams as he moved 10-6 ahead of second-round opponent Andrew Higginson, the 34-year-old Widnes cueman.

World number 36 Jones had breaks of 95 and 101, plus a gutsy clearance of 39 to pinch the final frame, doubling in the black to open up his four-frame lead, and Carter or Trump await the winner.

Another Welshman, two-time Crucible runner-up Matthew Stevens, scored heavily at times in the opening two sessions against Barry Hawkins as he fired in three century breaks, 101, 122 and 123.

However Hawkins led for much of the way and by the end of their second session the pair were tied at 8-8, with Stevens firing an 80 break in the final frame.