Ronnie O'Sullivan's bid to become the first player in 15 years to win three successive ranking titles remains on course after he reached the quarter-finals of the Shanghai Masters.
O'Sullivan, who captured the World Championship last May and the Northern Ireland Trophy in August, defeated Joe Perry 5-3 on a day when Jamie Cope made a maximum 147 break and still lost his match.
World number one O'Sullivan went off the boil against Perry after opening up a 3-0 lead, and the match could have gone the distance had he not cleared up from green to black in the eighth frame.
O'Sullivan's frustrations were evident as early as the third frame when he let slip an expletive and was warned for swearing by referee Brendan Moore.
In a conversation between the two before the fourth, Moore told O'Sullivan he would award a frame to Perry for any further transgression.
'It was a strange game and could have gone either way so I'm delighted to get through. Joe's a good player,' said O'Sullivan, who lost to Perry in the Premier League last month.
Stephen Hendry and Steve Davis are currently the only players in the game's history to have won three ranking events in a row, but O'Sullivan is now three wins from joining them.
Cope became the 10th player to compile more than one maximum in professional competition but was still beaten 5-2 by Mark Williams.
The world number 19 from Stoke previously made a 147 in the 2006 Royal London Watches Grand Prix in Aberdeen.
His latest maximum came in the third frame of his match against Williams and should earn him £22,000, but after winning the fourth frame the 23-year-old lost three in succession as his hopes of reaching the quarter-finals were sunk.
'I'd rather have won the match because I came here to win the tournament,' said Cope, runner-up in the 2006 Grand Prix and 2007 China Open but yet to land a title.
'It's getting on my nerves that I haven't won one yet. Overall, I'm disappointed. I hope no-one else makes a 147 to share the prize money but anyone is capable of doing it.'
Welshman Ryan Day defeated two-time world champion John Higgins 5-3 while world number two Stephen Maguire beat Stuart Bingham 5-3.
In earlier action, Welsh Open champion Mark Selby beat Mark King 5-0 to storm into the quarter-finals.
The 25-year-old world number four compiled breaks of 48, 68, 48, 44 and 68 to set up tomorrow's last-eight meeting with Marco Fu, who overcame Andy Hicks 5-2.
Selby said: 'I played really well. I didn't have many big breaks but I didn't give anything away either.
'I've played well in China over the last three tournaments so hopefully I can go one better this time.'
World number 35 Ricky Walden pulled off a stunning 5-4 victory over Australian Neil Robertson, having been 4-1 down.
Six-time former world champion Davis also advanced after a similar win against Northern Ireland Trophy finalist Dave Harold.
Veteran Davis came from 3-0 and 4-1 behind to claim a 5-4 win.
