Ronnie O'Sullivan may be uncertain of his place in the Embassy World Championship quarter-finals.

But the raging 'Rocket' looks destined to find himself in hot water with the game's governing body after another controversial flashpoint in his match with Andy Hicks at Sheffield on Friday.

O'Sullivan resumes on Friday night deadlocked at 8-8 with the 30-year-old Devon left-hander after a fascinating penultimate session.

But all the excellent snooker, including two O'Sullivan centuries - taking his match tally to four - has been undone by his latest hand gestures.

The Essex professional was clearly captured by the BBC cameras making an obscene signal after losing position in the final frame of the session.

It was much more noticeable than the one-fingered salute in his first round game against Stephen Maguire which did not attract censure from the World Professional Billiards and Snooker Association.

But they surely will not be able to ignore O'Sullivan's bizarre behaviour for much longer.

He also gestured towards the crowd at the end of a 125 break in frame 12, later insisting he had only been signalling to a friend in the audience.

However, O'Sullivan is just about keeping the lid on his famous temper which once resulted in a backstage attack at the Crucible on Mike Ganley, this year's tournament director.

He smashed his fist in frustration at another error in the 15th frame and again walked away from the table while Hicks was taking his shot in the opening exchanges.

It's to his credit that the world number 62 is managing to keep his concentration.

And if O'Sullivan's mental state continues to deteriorate when the match concludes with eight more frames, Hicks must have an outstanding chance to reach the last eight.

He has been behind only twice and while not quite matching O'Sullivan's high-scoring has been playing well.

Indeed, O'Sullivan almost gave his opponent a chance to lead 9-7 in the last frame. He carelessly went in-off, after recklessly potting the final pink.

Hicks obtained a further six points for a superb snooker but could not quite manage the two further pots which would have forced a re-spot.

Happily there were no further incidents at close of play, the duo shaking hands before disappearing backstage.

This evening's encounter promises to be the most dramatic session of the championship so far.