Ronnie O'Sullivan took obvious pleasure in putting Shaun Murphy to the sword as he hit top form in their Snooker World Championship tussle.

The five-time winner was looking in the mood for a sixth Crucible title as he built a 6-2 lead.

Rather than getting on famously, O'Sullivan and Murphy famously do not get on. O'Sullivan said bluntly at a literary festival last year that Murphy was a player he disliked.

"We don't relate," O'Sullivan told an amused audience.

And the division between the pair was laid bare again this week in Sheffield when Murphy picked apart the Rocket's complaint of bullying against World Snooker chairman Barry Hearn and the sport's authorities.

Murphy labelled O'Sullivan "our snooker celebrity" - but such remarks from the 2005 world champion only appeared to motivate his 41-year-old opponent.

And as he fired breaks of 91, 75, 128, 76 and 74 in streaking clear, O'Sullivan set up the possibility of beating Murphy with a session to spare, just as he did in their quarter-final three years ago when posting a savage 13-3 win.

The target is again 13 frames in this second-round match, which resumes on Friday afternoon and has another session scheduled for Saturday morning.

After a scratchy first-round win over Gary Wilson, O'Sullivan poured out his heart on Sunday when laying a host of accusations at the door of snooker's governing authorities, claiming they have singled him out for unreasonable treatment.

O'Sullivan's rival players have expressed mixed views about his complaints, with John Higgins and Neil Robertson sympathetic but Murphy emphatically saying the allegations were "completely wrong", in keeping with Hearn's own response.

But if O'Sullivan was trying to lift a weight from his own shoulders by going public, the move appeared to have brought the desired results.

He has not won back-to-back matches since landing his seventh Masters title in January, but put himself in line to achieve just that on snooker's biggest stage.

O'Sullivan might have led 6-1 but missed the black for the frame, and Murphy slotted it after a safety battle. But when a chance came early in the next frame, O'Sullivan pounced.

Murphy had said ahead of the contest that facing O'Sullivan was akin to "holding a lion by its tail". But with Murphy releasing his grip, O'Sullivan had his claws firmly into this most testy of contests. He will take some taming from here.