Snooker: Robertson hit for six by O'Sullivan's stunning comeback Ronnie O'Sullivan is looking ominously poised to win his fourth World Championship title after he marched into the semi-finals last night. The "Rocket," who trailed the 2010 champion Neil Robertson 5-3 overnight, returned to win six frames in a row and establish a slender 9-7 lead in their quarter-final. The triple world champion then held his nerve in the evening session to win 13-10. "I'm just out there to do a job," reflected O'Sullivan. I'd love to win another one but there's still a long way to go. Everyone here is still capable of winning this event. I thought Neil was the man to beat, and then you see [Stephen] Maguire play. It's just like the roll of a dice now. Robertson started the better by pinching the first frame of the concluding session with a break of 50, but O'Sullivan immediately hit back with runs of 104, 71 and 100 to pull four frames clear. But 2010 Crucible winner Robertson rallied with runs of 77 and 59, only for O'Sullivan to finish the job with a break of 59. "I'm just enjoying playing," added O'Sullivan. You've got to make the most of these occasions now. I'm just pleased to have had a little run in this, if I get through another match then great, if I don't it's no big deal. I've had a good go; I've enjoyed it. Next up is a semi-final meeting with Matthew Stevens, the Welshman, who won his quarter-final 13-5 against compatriot Ryan Day. Stevens was 5-2 down at one stage but strung together a remarkable winning run of 11 frames in succession for a fine victory. Day was left shell-shocked as Stevens dominated, although surprisingly the 2000 and 2005 world finalist managed to only compile two half-century breaks in the entire match. Meanwhile, Maguire has learnt from the disappointment of losing his only Crucible semi-final.He squandered a 14-10 lead in a 17-15 defeat to John Higgins five years ago, but said: "It's not an easy tournament to win, but hopefully it's going to be my time. It's going to be a long match in the semi-finals, but I'm going to take every session at a time and see what happens. Maguire will play the winner of Ali Carter, the 2008 runner-up, against qualifier Jamie Jones. Carter led that quarter-final 12-10 and was favourite to progress.