Ronnie O'Sullivan faced a Crucible ticking-off from referee Michaela Tabb but regained his focus to move within sight of a place in the Betfair World Championship final.
The defending champion lost all his concentration and looked bored as the penultimate frame of the night against Judd Trump became scrappy.
When he missed a ball he expected to rifle into the pocket he ran his hand up the shaft of his cue between his legs and Tabb stepped in to issue a brief reprimand, with O'Sullivan seeming to say "I wanna go home".
He denied trying to cause offence, arguing his cue was sticky and he was trying to solve the problem.
He lost the frame but took the last of the night to go 14-10 in front overnight, having led 9-7 at the start of the session, and just three away from his fifth World Championship final.
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.
Tonight he had breaks of 51, 62 and a closing 89 to punish Trump for a series of misses that suggested he was feeling the pressure of the semi-final occasion.