Ronnie O'Sullivan edged closer to his fifth World Championship final after opening up a 14-10 lead over Judd Trump on Friday evening at the Crucible.
The 'Rocket' faced a ticking-off from referee Michaela Tabb but regained his focus to move within sight of a place in the final.
The defending champion lost all his concentration and looked bored as the penultimate frame of the night against Trump became scrappy and was even heard saying "I wanna go home" during a safety exchange.
Having begun the day level at 4-4 in the match, to come through two sessions with a four-frame cushion was a fine achievement for O'Sullivan, who made breaks of 51, 62 and a closing 89 in the evening session.
The 37-year-old from Essex, who is aiming to win his fifth Crucible crown, had started the evening 9-7 in front in the race to 17.
Both players showcased their full repertoires in the afternoon and continued to deliver to the highest order entertaining a packed audience, not least than in the final frame of the afternoon.
The game's two main box-office stars were tied at 4-4 overnight and defending champion O'Sullivan twice edged ahead only to be pegged back each time before the interval.
O'Sullivan rattled off three frames in a row after the resumption to pile the pressure on the left-handed Bristolian.
The 'Rocket' responded to Trump's 30 with a quick-fire 43 in the 13th before producing a brilliant snooker on the green from which his opponent could not escape.
Seven became eight as O'Sullivan made a punishing 93 to the yellow before a run of 60 secured him the next. The world No 3 managed to claw one back in the final frame of the afternoon as both players entertained the crowd with some high quality safety play.
In the other semi-final clash Ricky Walden leads Barry Hawkins 9-7, but the latter will be the more pleased after coming into the second session 6-2 down.
In a nervy and edgy afternoon of snooker devoid of much quality, Hawkins took three of the first four frames to fight his way back into the contest.
However, after the interval, Walden responded with a break of 106 - his third century of the match - before Kent cueman Hawkins won the next.
In frame 15, Hawkins, 34, beat his highest break of the match (36) with a 47 before giving the Crucible audience a congratulatory fist pump.
The final frame of the day went to Chester-born Walden, who made sure he would have an overnight lead with a break of 53, but 'The Hawk' has clawed his back into the contest with a further two sessions to come on Saturday.