LONDON (AFP) - Defending champion Ronnie O'Sullivan was just six frames away from yet another appearance in the World Championship final after extending his lead against Barry Hawkins on Friday

O'Sullivan, aiming for a third successive world title and sixth in all, was 5-2 up overnight against Hawkins in what is a repeat of last year's final.

And the 'Rocket' stretched his lead over his fellow Englishman to 11-5 by the close of Friday's opening session at the Crucible Theatre in Sheffield, northern England.

The match resumes later Friday, when eight frames are scheduled, and should O'Sullivan win six of those he will give himself an unscheduled day off.

Indeed O'Sullivan might have been even better placed after sprinting into a 10-2 lead after breaks of 83, 53, 112 and 106.

But the battling Hawkins gave himself hope of a come-from-behind victory with a break of 106 in the final frame of the session, having won three out of four frames following the mid-session interval.

In the second semi-final, Mark Selby, who was 5-3 up overnight against Australia's Neil Robertson, the world number one and 2010 world champion, remained two frames in front at 9-7.

The Englishman had a chance to go 10-6 in front in the final frame of Friday's play but a mistake on the black allowed Robertson, who came from 5-1 down to beat Selby in the UK Championship final in December, back in and his clearance to the pink ensured the match remained finely balanced.

Their match resumes at 10.00am local time (0900GMT) Saturday and will be played to a finish later that day.