London — Snooker great Ronnie O’Sullivan insisted it was “not the end of the world” after he suffered a stunning defeat by amateur James Cahill in the first round of the World Championship on Tuesday.

In one of the biggest upsets in snooker history, Cahill beat five-time world champion O’Sullivan 10-8 at the Crucible Theatre in Sheffield.

Not since 2003 had O’Sullivan lost in the first round of the World Championship.

O’Sullivan, the world number one, had been in fine form heading into the world championship after winning five tournaments this season, compiling his 1,000th career century en route to victory in the Players Championship.

But the “Rocket” blamed a below-par display on illness and recurring bouts of insomnia.

“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% it’s just one of those things. If you could take a magic pill to protect yourself from this stuff you would.”

O’Sullivan tried to put his defeat into context by adding: “It’s just life, it’s not the end of the world... If I feel better Friday I’ll be really disappointed, if I still don’t feel too great it probably wasn’t the worst thing that could have happened.”

The 43-year-old, last crowned world champion in 2013, added: “It’s over, it’s done and now I can disappear and have a holiday and just enjoy the rest of the tournament.”

Earlier, O’Sullivan praised Cahill by telling the BBC: “He did well. He held himself together.”

Meanwhile Cahill, who came through three rounds of qualifying to make his Crucible debut, was delighted with a win over his snooker “idol”.

“I’m absolutely over the moon with that,” said the 23-year-old. “I’m glad to hold myself together against the best player in the world on my Crucible debut, it doesn’t get any better than that.

“You’ve got to believe you can beat anyone. I’ve got so much respect for Ronnie, he’s such a great player and my idol really, but there’s only so much respect you can have for these people because at the end of the day you have to go out and beat them,”  he said.

And with this win under his belt Cahill, who lost his status as a professional in 2017, was in bullish mood ahead of his second-round match against Scotland’s Stephen Maguire.

“I’m here to win the tournament,” added Cahill, who beat then-world number one Mark Selby in the opening round of the 2018 UK Championship.

“I play every tournament to win otherwise I wouldn’t play. You can’t come to a tournament thinking you’re going to get beat … or what’s the point in playing?”

Cahill extended his 5-4 overnight lead to 8-5 after the match with O’Sullivan resumed Tuesday. 

O’Sullivan pulled back to 8-8 with the aid of breaks of 104 and 89. But he missed a chance to take the 17th frame, leaving Cahill 9-8 in front.

O’Sullivan then had the opportunity to take the match to a final-frame decider, but he inadvertently potted a red when breaking the pack open from the blue.

Cahill made the most of an unexpected chance by holding his nerve with a break of 53.