Result: Amateur James Cahill stuns Ronnie O'Sullivan in one of snooker's biggest shocks

World number one Ronnie O'Sullivan crashed out of the World Championship in the first round after suffering a stunning defeat to amateur James Cahill.

In arguably the biggest shock in the tournament's history, Cahill held his nerve to beat five-time champion O'Sullivan 10-8 at the Crucible.

O'Sullivan was a prohibitive favourite before the match after a season which saw him win five titles and compile his 1,000th career century on his way to victory in the Tour Championship.

But after recovering from 8-5 down to get back on level terms with the aid of breaks of 104 and 89, O'Sullivan missed a great chance to snatch the 17th frame and Cahill took advantage to move 9-8 in front.

O'Sullivan looked on course to set up a final-frame decider only to inadvertently pot a red when breaking the pack open from the blue, leaving Cahill to produce a nerveless break of 53.

The 23-year-old from Blackpool will face Scotland's Stephen Maguire in the second round.

A delighted Cahill told the BBC: "I believe I can beat anyone on the day."

Asked how he managed to hold his nerve to pot the final few balls to clinch victory over O'Sullivan, he replied: "I don't really know. I thought I was going to fall over at one point.

"I thought I'd be nervous when I went out there today but I wasn't. I was a bit tense in parts but I think I have shown quite a bit of bottle.

"It was nice to qualify and it was nice to beat Ronnie."

O'Sullivan admitted he was feeling under the weather as he bowed out in the first round for the first time since 2003.

"My limbs are feeling very heavy. I have no energy," he said. "You come here and try to do your best but if you're physically not 100 per cent it's just one of those things.

"I tried to hang in there and get through this match and have a few days off before my next match.

"There are two ways of looking at it. One is, he has come here and played brilliantly. But I also left him some easy chances."