Ronnie O’Sullivan suffers shock defeat to amateur James Cahill in biggest upset in history

The world No 1, who had not lost in the first round since a 2003 defeat to Marco Fu, came into the day's play 5-4 down overnight and could not string any form together against the 23-year-old.

Five-time world champion O'Sullivan - who later admitted he felt 'shattered' - won the first frame of the day with a break of 97, but Cahill did not seem fazed before going 8-5 up.

O'Sullivan - who was 50-1 on to win the contest - however won three frames after the interval to go to 8-8.

However, he made a costly error on the pink in the following frame, before then throwing away a great opportunity at 9-8 down after a break of 42. Cahill stole in to clear up and take the match.

“I found it tough, I haven’t felt physically great for a while now I don’t know if I’m carrying a bug or something." O'Sullivan told Eurosport after the match.

“Some days I’m alright and some days I feel really shattered and tired. My arms and my legs just feel like lead and it was a struggle physically. Mentally I just tried to hang in there and see if I could manage to get through the match but it wasn’t meant to be.

The defeat had echoes of Judd Trump's loss in 2017, when he lost to 1,000-1 outsider Rory McLeod.

Bolton qualifier Tony Knowles beat defending champion Steve Davis 10-1 in 1982, but it wasn't his debut at event and was world number 20.

“I don’t really know what to say to be honest, it’s the best win of my career by far." Cahill told Eurosport.

“I just try to keep my eyes on the table and just play the shots as they come. I think I’ve got quite a good temperament for that sort of thing but you know in that sort of circumstance it’s not easy to hold yourself together and I’m just glad that I could.”