Ronnie O’Sullivan is in danger of crashing out of the World Snooker Championship after Mark Williams established a 6-2 lead in their quarter-final clash on Monday. Williams, bidding for a fourth world title, reeled off five consecutive frames at Sheffield’s Crucible theatre to take control of the best-of-25 tie. There was nothing to separate the veteran duo before the mid-session interval as they shared the opening four frames, which included a century from five-time world champion O’Sullivan. But just 24 hours after criticising the lack of quality opposition outside the sport’s top stars, O’Sullivan endured a poor run that puts his World Championship challenge in jeopardy. Ronnie O’Sullivan blasts snooker’s next generation Williams edged a scrappy fifth frame before propelling himself into a healthy position with breaks of 72, 56 and a superb 130. Meanwhile, Kyren Wilson moved into a 10-6 lead over defending champion Judd Trump in their quarter-final. Trailing 5-3 from the opening session, a frustrated Trump continued to be kept at arm’s length by Wilson as the pair initially traded frames. Wilson responded to Trump’s knock of 73 with a break of 65 to maintain his two-frame advantage. Ronnie O’Sullivan outlasts Ding Junhui in high-calibre last-16 display Trump, who beat John Higgins in last year’s final, again reduced the deficit to a single frame but then blew an excellent opportunity to level at 6-6 by missing a costly final black. The pattern continued as Wilson ensured he could not trail overnight with a superb 94 to go 8-6 ahead. He then pulled away, taking the final two frames to leave Trump facing an uphill battle on Tuesday. Elsewhere in the last eight, Mark Selby has built an 11-5 lead against Australia’s Neil Robertson. Selby edged a marathon 58-minute opening frame, the longest in this year’s tournament, and then reeled off the next four frames to race 5-0 in front. | On tonight’s Wrap - Ronnie O’Sullivan, Mark Williams, Kyren Wilson, Anthony McGill and Dennis Taylor #ilovesnooker | @WeAreWST pic.twitter.com/BD7NgOKUBS — BETFRED (@Betfred) August 10, 2020 However, Robertson hauled himself back into the match by winning the final three frames of the session, recording breaks of 83, 66 and 65. Selby, champion in 2014, 2016 and 2017, eventually ended the day six frames in front and with a last-four spot within touching distance after finishing with a fine break of 76. In the battle of the qualifiers, Anthony McGill already looks on course for a maiden Crucible semi-final. The Scot dominated the opening session of his meeting with Norwegian Kurt Maflin and will resume on Tuesday holding a commanding 7-1 lead.