O'Sullivan relieved after edging through

Ronnie O’Sullivan admitted he “never felt comfortable” during a stern examination by Neil Robertson as he reached the quarter-finals of the 888.com World Championship.

’The Rocket’ got the better of a high-quality tussle with the season’s form player to win 13-10, while 2002 champion and last year’s runner-up Peter Ebdon was beaten 13-8 by young gun Mark Selby at Sheffield’s Crucible Theatre.

Level at 8-8 with Melbourne’s Robertson going into last night’s deciding session after he had won six of the eight frames in the morning, O’Sullivan looked in danger of defeat when he trailed 10-9.

Most frames were being won at a single visit but after O’Sullivan had knocked in a 96 to make it 10-10, one shot ultimately proved pivotal as Robertson missed a pink with the rest to let in his opponent for a vital 44 that gave him the lead.

Having edged ahead, the two-time former champion was in no mood to surrender his advantage and he wrapped up his victory with a break of 87.

“I’m pleased to have got through,” said the 31-year-old from Essex, who will meet John Higgins in the last eight. “Neil pots so well and is dangerous among the balls, which can be quite intimidating.

“When someone is potting so cleanly and sweetly and hitting the back of the pockets with authority it is intimidating. He’s a bit of a powerhouse. You have to try to contain him.

“But I had to stamp my authority on the match too, although I never felt all that comfortable. If there was six foot between the cue ball and the object ball I was miles out.”

Robertson was happy with his performance and revealed he had stuck to his natural game in the hope that he could outplay O’Sullivan.

“I played really well and I’m proud with how I came back from 6-2 down this morning,” said the 25-year-old Cambridge-based player, the only man to have won two ranking titles this season.

“I didn’t bother trying to slow the game down and make people turn off their TVs, I tried to give it a go. I did my best but unfortunately I lost really closely.

“I’m disappointed I had to play that pink with the rest at 10-10 because I had a bad contact when screwing back from potting the red. If I’d had my hand on the table I would have gone 11-10 up and he would have been vulnerable from there.”

Ebdon did prove vulnerable against Selby, who emulated a feat previously achieved by O’Sullivan and Higgins by making three consecutive centuries during his win.

Those breaks put the 23-year-old from Leicester 8-4 up and he was always in control from that point, adding two further tons to his tally to go 12-8 ahead before scrapping his way over the line in the next frame.

“That’s probably the best match I’ve played in my career,” said the world number 28, who is into the quarter-finals for the first time.

“I always seem to play well against Peter but I knew he would fight to the end. Even if he was 12-0 down he would keep fighting. I was getting more and more nervous near the end.”

Ebdon, many people’s tip to capture the crown for the second time, admitted he had failed to bring his best form to the Crucible.

“Mark played tremendously well and thoroughly deserved to win,” said the Dubai-based 36-year-old. “He played the better snooker and is a very good player.”

Selby’s next opponent will be Ali Carter, who had earlier completed a terrific 13-6 triumph against seven-time former champion Stephen Hendry.