Judd Trump, who led the world snooker world championship against three-time winner Mark Williams, 7-1 after the first quarter of the semi-finals.
The two players have met 27 times before, with Trump having the advantage with 18 wins.
Judd Trump, who won the tournament in 2019, led Williams 3-0 in three consecutive sets after the semi-finals began.
Williams also returned to color before the mid-break, but after that Judd Trump did not give his opponents another chance and continued to extend the lead.
The duo's second quarter will resume at 10:00 a.m. local time, and Williams faces a huge challenge if they want to reach the final at Crucible for the fifth time.
In a quarter-final with Chinese player Yan Bingtao, Williams lost the quarter 2-6 due to his inability to concentrate.