Snooker: Ronnie races to win.
O'Sullivan has not won a ranking title for 32 months, but although he has admitted that does not worry him, he does want to improve.
"The scoreline flatters me massively. It was a win, but that was about it really," he said.
"There were far too many unforced errors for my liking and I can't allow myself to say that was good.
"Mark didn't punish me and I got a bit of luck. From 3-0, 4-0 down it's a tough way back. You never expect an easy game against Mark. He's going to make you work for everything you get, but Mark came out to play and he missed balls he shouldn't have really.
"Of course I want to play better. I want to improve, but I don't know whether I need to improve."
O'Sullivan will next play Stoke's Jamie Cope.
Hong Kong's Marco Fu beat Cambridge's Joe Perry 9-2, having led 7-1 after the afternoon session, and meets last season's world championship runner-up Mark Selby, after he too had a 9-2 victory over Stoke's Dave Harold.
The World Championship runner-up had breaks of 99, 120 and 48 to do most of the damage.
Scotland's Stephen Maguire made sure of his place in the quarter-finals with a 9-5 victory over Preston's Ian McCulloch. "Ian slowed the game down and made it hard for me, but that's up to him," said Maguire. "He did what he had to win, but I was never under pressure.
"Every time we both got in we're couldn't get a decent split on the pack (of reds), but from 5-3 I felt comfortable." In the last match to finish Cope won a tense final-frame decider to knock out Beckenham's Barry Hawkins.
The Shotgun, who dumped out world champion John Higgins at the first hurdle, pocketed a cool 105 break to go through.
The pair's last 16 clash was played in one of the side cubicles, which twotime ranking event runner-up Cope admitted he found difficult to get used to.
FLATTERED... Ronnie O'Sullivan.