The Rocket has won three titles at the Crucible, but lost his last outing in the final to Mark Selby, back in 2014. The 2020 competition starts on Friday, July 31 and you can watch it live on Eurosport.
"If someone said to me it’s in the bag, guaranteed, all you’ve got to do is turn up I’ll go, ‘Sweet,’ but it’s not like that," he told the Radio Times.
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"It takes a lot of preparation, blood, sweat and tears. I like to just go there and enjoy it.
"If I’m on, I’m a danger. If I’m not, an early exit suits me fine because I don’t want to go all the way to Sheffield and get beat in the final. That’s the worst result, it takes years off your career."
O'Sullivan also admitted that his preparations for the tournament will be greatly affected by the Covid-19 pandemic.

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“You can’t stay in the hotels you’d normally stay in. Usually I’d rent a house with my own food and a few friends with me and we’d just turn it into a holiday. The snooker is a bit of an add-on.
"All those things I could control, I’m not going to be able to do that stuff. Potentially, that’s quite worrying for me. How do you spend 17 days in an environment, eating food you’re not used to? It’ll be tricky.
"Some people live off Dominos pizza and deep-fried burgers and fried chicken, for them, eating a bit of Ryanair food in the hotel – that’s what the catering is like – their stomach’s going to deal with that whereas me, I’m probably going to make myself feel ill from that after a day.
"The resources World Snooker have isn’t great, so I imagine they’ll go down the low budget end, so I’m not sure how – health-wise – I’m going to cope with that. It’s all new. Normal, but new.
"It’s about whether it means that much to you anymore, if you want to go to prison for 17 days, sweat it out and go through that then great, but some people might not feel like that."
O'Sullivan, who has been vocal about his reservations about his plans to have fans in the Crucible, admitted that he enjoyed life during the UK's Covid-19 lockdown, during which he rarely practised snooker.
"Before Milton Keynes, I’d done about six or seven hours practice, that was all I’d done since February, but I was doing a lot of practice in the mirror. I have this mirror in my house and I’d cue up for about half an hour every day just to make sure everything was all in line. That’s all I was doing.
“It sounds crazy to say, but I’ve had an absolutely fantastic time [in lockdown]. Life’s got even more simple. I’ve always enjoyed the simple life and always thought there was something wrong with me for wanting to enjoy a simple life but actually I’ve come to the conclusion it’s good to be like that.
"You can’t go out to restaurants – not that I ever liked to – but it’s just made that impossible. Nice little takeaway sitting in my car eating it with the missus has turned out to be highlight of the week."
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