Ronnie O’Sullivan repelled a fightback from Luca Brecel to move three frames away from a place in the semi-finals of the World Snooker Championship in Sheffield.

Despite looking far from his best over the majority of the opening two sessions of their last eight clash, O’Sullivan preserved his early four-frame lead and will take a 10-6 advantage into Wednesday afternoon’s concluding session.

Twice Brecel pounced on uncharacteristic errors by the seven-time champion to haul himself back within two frames of levelling the match, only for lapses of concentration to prove his own worst enemy as O’Sullivan pulled away again.

The tournament favourite had struggled to rediscover the form that had swept him through his second round match against Hossein Vafaei with a session to spare, complaining that “it’s a hard game today” as he laboured through a scrappy fourth frame of their opening session.

O’Sullivan also thumped his leg in anger after missing a black in the seventh frame, but still managed to overhaul a 2-1 deficit and reel off five in row to take a convincing 6-2 lead ahead of their evening resumption.

The 28-year-old Brecel made a scorching start to the evening session as he responded to an early O’Sullivan miss with a break of 128 to reduce the deficit.

When O’Sullivan missed a rare black off its spot in the next, Brecel sensed a real chance to pull back in contention and a cool clearance of 33 took him firmly back into the contest.

But it was a position from which Brecel would singularly fail to capitalise, running out of position when he got the first chance in the next, then labouring through a disjointed 12th frame as O’Sullivan restored his four-frame lead at 8-4.

Once again the momentum swung back in Brecel’s direction, as consecutive breaks of 58 and a dazzling 81 took the Belgian back within two frames, but his raw talent could not disguise an inconsistency in his game that was to cost him dear.

A missed red to the middle blew Brecel’s hopes of capping another comeback, and O’Sullivan will count himself fortunate to have emerged unscathed from the evening’s action after he fought through the final two frames of the session to emerge unscathed.

Mark Selby racked up his 99th Crucible century as he hit back from a 4-1 deficit to earn a share of the opening session of his semi-final against fellow former winner John Higgins.

A series of uncharacteristic errors from Selby helped Higgins move into a commanding position but the Leicester man benefited from a fluked red midway through a break of 70 that helped him claim his second frame of the day.

Selby followed up with an 82 then rounded off an intriguing session with a clearance to black of 103 to ensure the pair will resume on Wednesday at 4-4.

Anthony McGill also fought back from 4-1 down to ensure he will also resume on Wednesday at 4-4 against Crucible debutant and fellow qualifier Si Jiahui.