|Lieu: Crucible Theater, Sheffield Appointment: July 31-August 16|
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Ronnie O’Sullivan and Judd Trump both face challenges to stay in the world championship after falling behind in their quarter-final matches.
Five-time winner O’Sullivan trails Mark Williams 6-2, with defending champion Trump 10-6 against Kyren Wilson.
Meanwhile, three-time winner Mark Selby leads 2010 Australian champion Neil Robertson 11-5.
In the last game of the last eight games, Anthony McGill established a 7-1 lead over Norway’s Kurt Maflin.
Trump entered Monday night’s session trailing 5-3 and looking for his best form.
And it turned out to be a frustrating experience for the world number one, who twice reduced his deficit to just one frame but lost the chance to level the game by missing the final black in the 12th frame.
The trend continued as Wilson, who won his first ranking title over Trump at the 2015 Shanghai Masters, gained confidence.
A superb break of 94 – the highest in the contest so far – and another of 80, helped the eighth seed build a noticeable lead as he clinched the final three frames.
Trump now faces an uphill battle when the best-of-25 game against Wilson ends Tuesday afternoon.
No first-time world snooker champion has retained the title since the tournament moved to its current location in 1977.
O’Sullivan battles vintage Williams
While five-time winner O’Sullivan has already demolished Thailand’s Thepchaiya Un-Nooh and beaten China’s Ding Junhui, facing three-time Welsh champion Williams was a step up in the class.
A high scoring start saw the former champions, both turning pro in 1992, trading frames with breakouts of 70 and 101.
But after the Englishman briefly edged ahead 2-1, Williams took control, compiling breaks of 72, 56 and 130 as he won five frames in a row.
Selby et McGill dominent
Selby holds the upper hand in his quarterfinal with Robertson, having dominated both sessions on Monday.
The Englishman is just two frames away from reaching the single table format for the first time since winning his third world title in 2017.
Selby, who edged an opening frame in the 58-minute marathon, the longest in this year’s tournament, established a 5-0 lead before the Aussie returned to the game with 83 breaks, 66 and 65.
However, Selby maintained his fine form on Monday night, winning the session 6-2.
In the qualifying battle, Scotland’s Anthony McGill is already on track for a first Crucible semi-final after taking charge of his opening session with Norwegian Kurt Maflin.
McGill advanced to the quarter-finals after making a remarkable comeback to beat compatriot Jamie Clarke 13-12 in a in a bad mood meet.
Meanwhile, the second and final round of coronavirus tests at the tournament did not yield any positive results.
There were 120 tests on players, officials and staff before the game started on Monday.