But, helped by some devastating break building, the Essex ace potted his way out of trouble and into the quarter-finals of the £666,000 event.

The high spot of an exciting contest came in frame eight as the world number two finally regained parity.

He produced an outstanding clearance of 143 to overtake Ken Doherty's 141 for a £7,500 high break prize. Earlier, he had fired in runs of 102 and 131.

Unsurprisingly, there were no more fireworks in the decider but O'Sullivan's contributions of 27 and 38 were sufficient to take him into the last eight.

"It was a good match but it doesn't matter whether you knock in all the breaks in the world if the other fellow is doing the same," said O'Sullivan after his 5-4 success.

"Then it's down to a toss of a coin and that's how it turned out."

In the past, O'Sullivan's agitated mental state could easily have seen him throw in the towel at 3-0.

However, he knuckled down to the task and said later: "When you feel you are playing okay then you feel like it's worth trying.

"Sometimes I knew even if I won one match, I'd struggle in the next so it wasn't worth the effort.

"But I feel like I am cueing a bit better and that's when you have got to make the most of it. I feel there is a bit of consistency coming into my game," added O'Sullivan who revealed earlier this week he had parted company with coach and mentor Derek Hill.

"I'm pretty optimistic. I've always practised hard to try and find the magic spark. I asked a few people what was going wrong and while I've not really found it I feel I'm making a steady improvement to my game."

Joining O'Sullivan in the quarter-finals is John Higgins, who also found a determined opponent blocking his route.

Forced to share the opening four frames with Dave Harold, Higgins cut loose after the interval to out-score his Stoke rival 255 points to 13.

"I won the Regal Masters last month for my wife Denise so it would be nice to win this one for my son Pierce," said the happy Scot.

"I do want to see them as much as possible but Denise says I've got a job of work to do and she's right."

Higgins became a dad for the first time but will not see his wife and son until Monday if he can add the British Open crown to his Masters and Champions Cup successes.

Higgins plays world number six Stephen Lee for a place in the semi-finals while O'Sullivan tackles Alan McManus, who earlier defeated Irishman Ken Doherty 5-4.