Mark Williams won six of the last seven frames to beat Judd Trump 10-4 and reach the semi-finals of the Tour Championship for the first time.
Following victory over the world number two, the Welshman, 49, will meet Mark Allen for a place in Sunday’s final.
Third-ranked Allen, 38, won seven of the last nine frames as he battled back to defeat China’s Ding Junhui 10-8.
Gary Wilson will face Ronnie O’Sullivan in the other semi-final after edging out Zhang Anda 10-8 in Manchester.
O’Sullivan progressed by thrashing Ali Carter 10-2 on Wednesday, after which he admitted he has had to change his thinking and “go back to basics” following a “hard year”.
In a scrappy contest, Williams clinched three frames on the black against Trump as both players made just two breaks over 50.
Meanwhile, Northern Ireland’s Allen came back from 6-3 and 8-7 down to overcome Ding, registering the highest break of the tournament so far with 142 in frame 10.
That semi-final will take place on Saturday (13:00 BST), after Wilson – who battled back from 8-7 down against Zhang – takes on seven-time world champion O’Sullivan on Friday (13:00).