Ronnie O'Sullivan and Judd Trump remain on course to meet in the final of the Northern Ireland Open for the third year in a row after reaching the quarter-finals of this year's event.
O'Sullivan made the last eight of the tournament, which is being played in Milton Keynes, by beating Thailand's Thepchaiya Un-Nooh 4-2 in round four.
Defending champion Trump saw off Martin Gould 4-1 at the Marshall Arena.
O'Sullivan now faces Ding Junhui, with Trump taking on Scott Donaldson.
'Was that you?'
The world champion admitted he was suffering from stomach problems after loudly breaking wind midway through his first match of the day against Matthew Stevens.
O'Sullivan - nicknamed 'The Rocket' - appeared to apologise to Stevens before turning to embarrassed referee Ben Williams and joking: "Was that you?"
But later O'Sullivan told Eurosport: "I am taking full ownership of that. I have had stomach problems for a couple of months.
"I did say 'was that you' to the referee but I am proud of that one."
O'Sullivan looked uncomfortable for long periods of his second match against Un-Nooh, but after reeling off the last two frames he said: "I'm all right - I've just got lots of gas and lots of wind."
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Scotsman Donaldson followed up his 4-1 victory over Mark Allen in round three by defeating Noppon Saengkham 4-1 in the fourth round on Thursday night.
China's Ding beat Scotsman John Higgins 4-1.
The remaining two best-of-nine-frame quarter-finals on Friday will see Ali Carter play Kurt Maflin and David Grace face former finalist Yan Bingtao.
World number one Trump has beaten O'Sullivan in the last two Northern Ireland Open finals, which were staged at the Waterfront Hall in Belfast, so is chasing a hat-trick of titles.
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