Ronnie O'Sullivan found himself in more bother at the Betfred World Championship after making a rude gesture during his second-round match against Matthew Stevens . On the table the five-time world champion enjoyed a successful day , firing two rapid centuries in establishing a 12-4 lead , needing just one more in Monday 's closing session to the match to reach the quarter-finals . But O'Sullivan was also spoken to by the referee Olivier Marteel towards the end of the afternoon session - and warned about his behaviour . Ronnie O'Sullivan is spoken to by referee Olivier Marteel in his second round match against Matthew Stevens . O'Sullivan is spoken to by referee Marteel in his second round match against Stevens at the Crucible . Marteel approached O'Sullivan as he walked to the table when Stevens missed a red , telling O'Sullivan he had noticed his hand gesture , which was thought to have been self-directed . O'Sullivan avoided a fine in the first round when he briefly played without shoes after a new pair proved uncomfortable , breaking the rules but not sufficiently to warrant any punishment , after he accepted a substitute pair of size eights , loaned by tournament director Mike Ganley . Stevens reacts to a shot in his match against O'Sullivan during day nine of World Championships . Stevens in action against O'Sullivan in their second round match at the Crucible Theatre . The warning from Marteel could be the end of Sunday 's matter . Yet any repeat of the incident would see O'Sullivan docked a frame , a tournament spokesman confirmed . Armed with a 5-3 lead from the opening session , O'Sullivan took the opening two frames on Sunday to pull further in front . The next went against the 39-year-old , but breaks of 110 and 139 in consecutive frames suggested O'Sullivan was in unstoppable form , as sweeping through the subsequent three testified . O'Sullivan in action against Stevens in their second round match at the Crucible Theatre in Sheffield . Ali Carter continued to struggle in his match against Australia 's Neil Robertson . The 35-year-old from Essex , who trailed 6-2 following Saturday 's opening session , won the first frame of the day but lost the next five . A finish with a session to spare was possible when Robertson led 11-3 , but Carter took the last two frames of the day to avoid that indignity and trail 11-5 overnight . Earlier , Shaun Murphy left Joe Perry with a mountain to climb as their second-round clash got under way , surging 7-1 in front , while Judd Trump built an early 5-3 lead over Marco Fu .
Ronnie O'Sullivan is closing in on World Championship quarter-final spot . But , he found himself in a spot of bother with referee Olivier Marteel . O'Sullivan was warned about his behaviour after obscene hand gesture . one-time world champions needs Five more frame to secure progression .