Reigning BDO world champion Glen Durrant scraped into the quarter-finals of the 2019 tournament with a 4-3 win over fellow Englishman Scott Baker.
Durrant, a Lakeside winner in both 2017 and 2018, took the opening three sets, before Baker clinched the next three.
But Durrant took the deciding set 3-1, hitting double 12 to win the match.
Former BDO world champion Scott Mitchell also advanced into the last eight, thanks to a 4-0 win over Poland's Krzysztof Kciuk.
Sixth seed Mitchell, 48, will play third seed Jim Williams of Wales, with Durrant facing Northern Ireland's Kyle McKinstry, who beat Canada's David Cameron 4-3.
In the women's event, top seed Lorraine Winstanley reached the semi-finals with a 2-0 victory over 10-time champion Trina Gulliver.
Winstanley next plays three-time winner Anastasia Dobromyslova, the runner-up last year, after the Russian beat fifth seed Aileen de Graaf of the Netherlands by a 2-0 margin.
Unseeded Maria O'Brien gained a 2-0 quarter-final win over sixth seed Fallon Sherrock.
It is the second seeded player O'Brien has knocked out after she beat three-time runner-up Deta Hedman in round one on Sunday.
Elsewhere, Japan's Mikuru Suzuki gained a shock 2-0 win over seventh seed Sharon Prins.
In the opening match of the afternoon session, Leighton Bennett, 13, became the youngest-ever winner of the BDO World Youth Championshipwhen he beat 16-year-old Scottish player Nathan Girvan 3-0.