LONDON, Aug. 11 (Xinhua) -- Ronnie O'Sullivan came from 8-4 down to defeat Mark Williams 13-10 on Tuesday, reaching the semifinals of the Snooker World Championship for the first time since 2014.
Earlier, reigning world champion and world number one Judd Trump was knocked out by eighth-ranked Kyren Wilson 13-9 in the quarterfinals.
O'Sullivan, 44, defeated China's top player Ding Junhui 13-10 on Sunday to book a quarterfinal berth. He struggled in Monday's opening session as he trailed Williams 6-2, but the five-time world champion came back strongly on Tuesday afternoon, drawing 8-8 with Williams after the second session.
In the concluding session, the Rocket played the upper hand to seal the win, reaching the semifinals for a record-equalling 12th time.
"For me, there were a lot of nervy moments," said O'Sullivan. "I was struggling with certain parts of my game so I had to maximize my opportunities when they came up."
O'Sullivan will face three-time world champion Mark Selby, who crushed Australian Neil Robertson 13-7.
"Mark Selby and I have had a lot of finals and big matches. We have both done well in the biggest tournaments. If I can find some control in my long game, manage to manipulate the ball and keep it on line, that will give me more confidence to give him a game," said O'Sullivan.
The 28-year-old Wilson, who gave a blow to Trump by winning eight of their 13 meetings, will lock horns with Anthony McGill from Scotland, who reached the semifinals of the World Championship for the first time by beating fellow qualifier Kurt Maflin 13-10.