On 26 March 2006, Williams won his 16th ranking event (and his first in two and a half years), the China Open in Beijing, beating Higgins 9–8 in the final. This helped him return to the top eight in the world rankings, after a dramatic fall in the provisional rankings which saw him facing a possible drop out of the top 16. He also showed good form in the 2006 World Championship, beating Anthony Hamilton 10–1 and Mark Selby 13–8 to set up a quarter-final clash with Ronnie O'Sullivan, the first time the two had met at the Crucible. The match was given extra tension considering they had been rivals (although O'Sullivan has since said that the former feud has been replaced by friendship and respect). In a close-fought match, O'Sullivan eventually won 13–11. It was revealed during that tournament that Williams had split with coach Terry Griffiths. The two remained very close friends, but Griffiths would no longer be coaching him. In late 2007, Williams returned to having Griffiths as his coach.