German qualifier Michael Unterbuchner caused another upset by beating 14th seed Martin Phillips to reach the quarter-finals of the BDO World Championships at Lakeside.
Having shocked third seed Jamie Hughes in round one, the 29-year-old led 2-0 before Wales’ Phillips levelled.
But Unterbuchner responded to complete a 4-2 victory, averaging 88.88.
He will face 11th seed Richard Veenstra in the last eight, after the Dutchman thrashed sixth seed Geert de Vos 4-0.
Wales’ ninth seed Jim Williams survived three match darts to beat Conan Whitehead 4-3 and set up a quarter-final with defending champion Glen Durrant.
In the women’s event, top seed Deta Hedman saw off Sharon Prins to set up an all-English semi-final with defending champion Lisa Ashton, who beat compatriot Fallon Sherrock.
England’s 10-time winner Trina Gulliver beat Dutch second seed Aileen de Graaf and will meet three-time winner Anastasia Dobromyslova in the other semi-final, after the Russian beat third seed Lorraine Winstanley.