Ronnie O'Sullivan tonight vowed "this is my last farewell" as he announced he would quit snooker for good before next year's Betfair World Championship.

The four-time champion at the Crucible is firm favourite to land a fifth title, having marched through to a semi-final clash with Judd Trump in fine style, beating Stuart Bingham 13-4 in the last eight.

O'Sullivan has spent most of the last 12 months in self-imposed exile from the sport, but returned for another shot at glory in Sheffield.

He now claims that decision was motivated purely by money, explaining how he needed to cough up for overdue school fees that he had no other means of paying.

The 37-year-old said: "It's nice to be in the semi-finals but I didn't really miss snooker.

"But I missed having something to do and I was struggling for a bit of money.

"I'll be honest, I still owe the school money for my children's school fees, I haven't paid the last two or three terms.

"I didn't know what was going to happen here but I've made a little bit of money now so I can go and pay the school fees now for the next two years.

"But really I don't think snooker is for me. This could be my last proper major event.

"As far as putting my heart and soul into snooker, I don't think that's what I want to do anymore but I had to give it a go. I needed some money quick.

"I have signed a contract with my sponsor to play in 10 events so I'll play in those."

But O'Sullivan stated those events could include Legends tour events, and low-profile tournaments, and stressed there was no stipulation that he should appear at events such as the UK Championship, Masters or World Championship.

Asked if he would be in Sheffield for next year's World Championship, O'Sullivan added: "I've no intention to come back.

"If I find something else to do you definitely won't see me.

"I've kept my cards close to my chest but there's no reason to keep them close now.

"This is my last farewell, it's my swansong. I'm happy; I'm done.

"I can't keep putting myself through being unhappy.

"I wish I could just smile it off, shrug it off but it's not like that for me. I wish I had the attitude of players who come here and smile and enjoy it. I just beat myself up too much and it's not healthy."

Every retirement warning from O'Sullivan needs to be treated with caution, as they have come so frequently during his career.

O'Sullivan at least vowed he would be giving it his all against Trump over the next three days, and in the two-day final.

"I'll be out there trying my nuts off," he said. "I'm a competitor and I hate losing. I will fight to the death. They'll have to scrape me off the table.

"I've got five days left potentially, it could possibly be three, and if I can't get through that then something's seriously wrong.

"The light at the end of the tunnel is it doesn't have to go on any longer."

Trump said he is not scared of O'Sullivan and their clash promises to be a classic, just like Trump's 13-12 quarter-final victory over Shaun Murphy.

Trump had clinched his final-frame victory over Murphy in the afternoon and came out fighting afterwards, saying: "There are only a certain amount of players who have got the self-belief to beat Ronnie and scare him and I think I'm one of them.

"I've got a good record against Ronnie. I've beaten him more times than he's beaten me, so hopefully I can go out and scare him.

"I think people are just scared of the name. The big stage is where I want to be. I'm not scared of the name."

O'Sullivan responded to that by saying of Trump: "I've played him a few times and I've sensed he's wobbled. Even he gets scared of me.

"It's a hard place out there. If you play well enough and stay with him, and peg him back, he's not Stephen Hendry or John Higgins."

O'Sullivan's remarks overshadowed what had been a thrilling finale to the match between Trump and Murphy, and also came on a day when Ricky Walden and Barry Hawkins reached Crucible semi-finals for the first time.

They go head to head in the first of four sessions tomorrow evening, with Trump and O'Sullivan getting under way in the afternoon.

Kent man Hawkins, 34, ousted former UK and Masters champion Ding Junhui, turning a 9-7 overnight lead into a 13-7 victory.

Hawkins said: "It means everything to be in my first semi-final. I've been trying so hard for so long to make some sort of breakthrough.

"To come here and get to the one-table set-up is a dream come true."

Walden, 30, saw off 21-year-old Welsh qualifier Michael White 13-6 and said: "I'm overjoyed with that. It's been good so far and I'm pleased to be in the semis."