World no 1 Impress Selby and Ronnie O’Sullivan were knocked out of the Welsh Begin.
Iran’s Hossein Vafaei defied a world rating 37 places below Selby to raise 4-3 within the closing 16 in Cardiff.
Joe O’Connor, ranked 102nd, beat world number eight Ding Junhui 4-1 to be triumphant within the quarter-finals.
Earlier, Switzerland’s Alexander Ursenbacher, ranked 71 on the planet, beat five-time world champion O’Sullivan 4-2.
Nonetheless, Ursenbacher’s celebrations were short-lived as he fell 4-2 against China’s Zhao Xintong within the closing 16.
Stuart Bingham will face Zhao within the closing eight while Joe O’Connor will play Scotland’s John Higgins.
Neil Robertson will prefer on Kurt Maflin while Scott Donaldson faces Vafaei.
Higgins beat England’s Jack Lisowski 4-3 to make the quarters, having earlier beaten one more Englishman, Craig Steadman, 4-2 within the third spherical.
Ticket as much as My Sport to study snooker news on the BBC app.