Mark Williams in control against Ronnie O’Sullivan at the Crucible

O’Sullivan, who controversially questioned snooker’s next generation, was second best and left with plenty to ponder

Five-time champion Ronnie O’Sullivan faces a battle to stay in the World Championship after Mark Williams hit form to build a commanding lead in Sheffield.

Welshman Williams, seeking a fourth world title of his own, won five consecutive frames at the Crucible to establish a 6-2 overnight advantage in the best-of-25 quarter-final.