Ronnie O’Sullivan is still hunting Crucible glory after all these years and moved a step closer to a sixth world title on Friday.

Twenty years to the day since he produced perhaps the greatest break of all time in Sheffield, it was a clutch clearance against Shaun Murphy rather than a sustained slice of O’Sullivan magic that kept him firmly on course for another shot at the trophy.

On April 21, 1997, O’Sullivan dashed to a 147 maximum break in just five minutes and 20 seconds against Mick Price, however it was a run of just 25 that provided cheer this time for the 41-year-old Rocket.

After letting Murphy cut his arrears from 9-3 to 9-6, O’Sullivan looked like allowing the last frame of the session to slide by too until his opponent missed green with the rest.

Murphy’s mistake gifted O’Sullivan the chance he was waiting for, and he calmly cleared the table from green to black to move 10-6 in front overnight, three frames away from victory in the second-round clash.

O’Sullivan’s famous maximum earned him £165,000 two decades ago, but with the reward this year a relatively meagre £15,000 there has been scant interest from the top players in gambling on the pursuit of successive reds and blacks.

Such breaks typically involve high risks, and O’Sullivan is all about getting the job done at the 40th anniversary Betfred World Championship.

He and Murphy return on Saturday morning, with the latter knowing he must make a fast start.

Murphy at least made sure he avoided a repeat of his 13-3 humbling by O’Sullivan at the last-eight stage three years ago.

The 34-year-old began 6-2 adrift on Friday afternoon and made an ideal start with a break of 70 before O’Sullivan responded with 63 and 75 to stretch his lead to five frames, which soon became six.

Murphy charged back with 84, 73 and 87, as pressure began to mount on O’Sullivan.

When Murphy fluked the yellow in the final frame of the day, surely O’Sullivan feared the worst. But the green would not drop for Murphy, the 2005 world champion, who saw the prospect of a narrow two-frame deficit substituted for the harsh reality of a four-frame chasm.

O’Sullivan and Murphy are far from friends, a sense that was reinforced when Murphy this week forcefully denounced O’Sullivan’s accusations of bullying against Barry Hearn and World Snooker.

The frosty relationship has been reflected in their lack of interaction during the match, but the opposite was true of the players on the other side of the arena.

Mark Allen took the fight to John Higgins on the table, but Scotland’s four-time world champion dug in to be just two frames behind overnight.

Northern Irishman Allen fired 71, 65, 100, 102, 129 and 82 and on that form would have hoped to finish better than 5-3 ahead, the outcome at the end of the session. The pair chatted away in their seats between frames – a stark contrast to the awkward silences between Murphy and O’Sullivan.

Ding Junhui went from 6-2 up on fellow Chinese cueman Liang Wenbo to 9-7 ahead, the gap narrowing in a high-quality encounter that finishes on Saturday afternoon.