At the 2011 World Snooker Championship, Williams defeated Ryan Day 10–5 in the first round, and Jamie Cope 13–4 in the second round. He then won his quarter-final against Mark Allen 13–5, and in doing so he reached the semi-final stage for the first time since 2003, but lost 14–17 against John Higgins. As a result of Selby's exit from the tournament Williams became the new world number one after the event.