Ronnie O'Sullivan claimed his head is strong and his game is trying to keep up after sprinting to an emphatic opening win over Peter Ebdon at the World Championship.

The 36-year-old was tormented by a loss to Ebdon in the quarter-finals seven years ago, and this was their first Crucible meeting since.

It was wholly one-sided, despite Ebdon saying O'Sullivan would need to improve in later rounds.

Seeking a fourth world title, and his first since 2008, O'Sullivan led 7-2 overnight and kept comfortably clear to register what should have been a thoroughly satisfying win.

O'Sullivan was far from trumpeting his own title prospects afterwards though, saying: "It's each match at a time really, there's no point getting carried away.

"I've had a decent season, but it would be nice to win a few matches here."

Yet O'Sullivan is particularly confident in his mental strength for the challenges which lie ahead. Working with sports psychiatrist Dr Steve Peters has fortified him for match play.

"My attitude was good. It's been really good all season," he said.

"Even though I've not been playing great I've not been beating myself up too much if things aren't going right for me.

"I've been working on that side of my game for the last year or so and that's important. I'm definitely much better mentally. My game's not brilliant, but at least my mind is allowing me to give 110% and get what I can out of matches, so I'm pleased with that side of things.

"If I win, then great, but if I don't it's not the be-all-and-end-all. I'll just enjoy this one."

In the second round O'Sullivan could face another world champion, two-time winner Mark Williams who starts his first-round match against Liu Chuang tomorrow.

Ebdon, frustrated not to perform as he did when winning the China Open at the start of the month, saw room for improvement in O'Sullivan's performance.

"Ultimately I don't think Ronnie has really had to play that well to beat me," Ebdon said.

"I think certainly he's going to have to improve a lot in his next match."

But Ebdon stressed his conqueror had every chance of finding the form required, saying: "You can't write that man off, that man is an absolute genius, one of the greatest players of all time.

"And as we saw in that match, even though he didn't play particularly well, there were four or five occasions of sheer brilliance and inspiration. He's just fantastic to watch."

Judd Trump withstood a bout of suspected food poisoning to edge ahead of Dominic Dale as last year's runner-up returned to the Crucible.

The 22-year-old English potter was unusually subdued in the early stages, with illness leaving him feeling weak, and when he trailed 3-1 at the mid-session interval it seemed he was in trouble.

At that stage, Trump might have taken a 5-4 deficit, but instead he leads by that scoreline overnight, an ideal state of play considering his ill health at the start of play.

Trump's management believe he became sick after eating a chicken dish, and he continued to feel ill after the session was over.

While Dale trailed, his fellow Welshman Ryan Day pulled 5-4 in front of China's Ding Junhui, the player Trump beat in the semi-finals last year.

Ding and Dale will feel they both have the opportunity to turn around deficits tomorrow, but it will be tough for Graeme Dott to come back against Joe Perry after the Scot, who was world champion in 2006, fell 8-1 behind against English opponent Joe Perry.

Perry had a highest break of only 54, but Dott endured a thoroughly dismal session.

Qualifier Andrew Higginson, from Widnes, caused an upset of a kind this evening by knocking out world number eight Stephen Lee, who lost in the first round for the sixth successive year, this time by a 10-6 margin.