The five-time champion fought back from a 7-2 deficit to defeat Mark Williams 13-10 but told Eurosport’s Colin Murray after the match that he feared being on the end of a heavy defeat.
"I was just pleased I made a game of it in the end. I was just scared that maybe I might not be able to make an impact on it, get beat 13-2, 13-3, a good mauling,” said O’Sullivan.
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Ronnie O'Sullivan: Mark Selby is a certainty, I've got no game!
"On the practice table this morning I thought I've got to find something that will allow me to score because I wasn't cueing well. So I thought anything over three feet from the white, the table looked 40 feet long.
"But in the balls, I was able to manufacture stuff, it was like a golfer couldn't find the fairway but, in the greens... I played snooker like Seve Ballesteros.”
O’Sullivan, 44, added that he has much work to do ahead of his semi-final with Mark Selby, describing his cue action as the world’s worst.
Ronnie O'Sullivan finishes off Mark Williams on re-spotted black
"If I can find a cue action – if someone can give me a cue action then I’d be over the moon. My cue action is the world’s worst. I fancy winning tournaments. I think Mark [Williams] will think he lost that one really.
"I think Mark Selby is a certainty - I've got no game."
The semi-final between Selby and O’Sullivan begins on Wednesday at 7pm, live on Eurosport, followed by an afternoon session on Thursday and then morning and evening sessions on Friday.
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