O'Sullivan let a winning position slip against Fu
Ronnie O'Sullivan joined the list of casualties at the China Open in Beijing after he was beaten 5-4 by Marco Fu.
O'Sullivan had led 4-3 and took an early advantage in the decider but missed a difficult blue to gift the first-round match to his rival.
He now follows former world champions Stephen Hendry, Steve Davis and Graeme Dott out of the tournament.
Earlier, John Higgins, Mark Williams, Peter Ebdon and Shaun Murphy all booked their second-round spots.
Current world champion and world number one Higgins made just one break over 50 but emerged a 5-4 winner after a tense victory over Joe Swail.
Williams's top-32 place has been in jeopardy but he was in impressive form.
He lost the first frame against Scottish qualifier Marcus Campbell before pocketing breaks of 66, 110, 101, 49 and 40.
"That was a really good win for me," said Williams.
"I needed to win to stay in the top 32, so hopefully this will be the springboard for more victories before the end of the season.
"It takes a while to adjust to coming to China, but I came out a few days before the tournament started.
"I have a good record here and the crowds are always good so I like playing here.
"That has to be one of the best matches I have played for a few months, so I can hopefully go on and play well in this tournament."