Stiffer tests lie ahead but Ronnie O'Sullivan returned to snooker today with a victory and a performance that suggests he will take some stopping in the Betfair World Championship.

The defending champion beat Scotland's Marcus Campbell 10-4 to set up a second-round clash starting next Saturday against either Ali Carter, the man he beat in last year's final, or Crucible rookie Ben Woollaston.

There was some early rust in O'Sullivan's game, but he could afford that against an opponent who seemed to freeze in the spotlight.

Campbell could have led 4-1 at one stage, but instead he trailed by that score after O'Sullivan pinched three frames and once the four-time champion settled into a rhythm there was no hope for the 40-year-old underdog.

O'Sullivan led 7-2 after the opening session and tonight returned with breaks of 102 and 90 before Campbell briefly delayed the inevitable.

Since battering Carter to carry off the trophy last year, O'Sullivan has taken a career hiatus that he intended to run longer than it has.

Announcing in November he would be sitting out the rest of the season, O'Sullivan had a change of heart by February and despite turning up with no match preparation under his belt he was almost playing another game to Campbell.

Breaks of 82, 62, 71, 85, 86 and 58 before lunch indicated O'Sullivan had been practising as diligently as he has reported.

A raucous reception greeted the 37-year-old as he strode out shortly after 10am and he responded with some early magic as his friend, the artist Damien Hirst, watched on.

O'Sullivan, who began the match by playing a left-handed break-off shot, soon sank four reds and four blacks and if a maximum 147 break did not enter his mind, it certainly did others.

He took blue off the fifth red, so it would not be a fairytale opening frame, but he still progressed serenely towards what looked sure to be a century.

He reached 82 but missed his next red, thus reducing it to a frame-winning break and nothing more. Not perfect, but remarkably given the circumstances it was not a world away.

O'Sullivan managed to lose the next frame from 49-0 ahead as Campbell levelled with a brilliant doubled pink.

It was the last time Campbell would be level though as O'Sullivan made him pay for failing to convert handsome leads into frames won.

O'Sullivan's 86 in the eighth frame featured one particularly exquisite left-handed pot on the pink that he played with screw and side, showing who was in charge.

Curiously, Campbell is ranked a place higher than O'Sullivan - 27th to 28th - but that can be explained by the world champion's inactivity this season.

Any slim hopes Campbell carried into the evening were wiped out inside half an hour as O'Sullivan piled on the misery with his two biggest breaks of the match.

A fluked green helped Campbell make it 9-3 and he clawed his way back to 9-4 to force an interval, but there the recovery ended.

An audacious plant helped O'Sullivan stay at the table to make 40 in the 14th frame. Campbell showed a further flicker of fight but frame and match were soon over.

Jack Lisowski's Crucible debut proved anticlimactic as the 21-year-old hot prospect fell 6-3 behind against Kent's Barry Hawkins.

World number four Shaun Murphy ran into early trouble against qualifier Martin Gould before the 2005 champion dug himself out of trouble to lead 5-4 overnight. They play to a finish tomorrow evening.

Chester's Ricky Walden made a break of 140, making him the early frontrunner for the £10,000 top-break prize, in building an 8-1 lead over Nottingham's Michael Holt.

Michael White leads his Welsh compatriot and former champion Mark Williams 5-4.

Tomorrow morning's concluding session to that match was looking a formality.