Ronnie O’Sullivan and Mark Williams took command of their respective quarter-finals on day 11 of the World Championship in Sheffield.

O’Sullivan benefited from an error-strewn display from Stephen Maguire to open up a 6-2 lead following their opening session, with Williams leading Yan Bingtao by the same margin after winning four frames in a row.

Maguire won a scrappy opening frame which had threatened to degenerate into a stalemate, with the green, brown and blue all clustered around the same corner pocket, but O’Sullivan quickly levelled the scores and moved in front with a run of 54 in the third.

The six-time champion looked unhappy with the state of his tip on several occasions but stretched his lead with the aid of breaks of 70 and 123 before Maguire crucially won an eventful eighth frame.

The Scot initially missed an attempted double on the final red and then went in-off when he did double it following an O’Sullivan safety, but O’Sullivan failed to pot the yellow to the middle and Maguire gratefully cleared up.

Yan fought back from 2-0 down with breaks of 102 and 85, but Williams found his scoring touch after the mid-session interval to produce breaks of 60, 106, 72 and 77, Yan failing to pot a single ball in the last three frames.