Former World champion Ken Doherty battled back from an early deficit to trail by a single frame (5-4) after his first session against Stuart Bingham at the Crucible.

Doherty looked in trouble early on in his Dafabet World Championship first-round clash as Englishman Bingham raced into a 3-0 lead, clinching the third frame on the black.

The Ranelagh man fought his way back into contention however, winning three of the next four frames and posting a break of 91 in the seventh.

Both players missed pottable chances in the eighth before Bingham wrapped it up but Doherty clung in in the ninth and final frame of the session to stay in contention in the best of 19 clash.

The tie will resume at 10.00am Sunday.

Meanwhile, defending champion Ronnie O'Sullivan was straight into an ominous groove as he opened a commanding 7-2 lead over Robin Hull.

Finnish potter Hull retired in 2008 after coming down with a life-threatening virus, but he felt able to return three years later and has played sporadically since, beating  former champion Peter Ebdon to qualify this week.

Yet the 39-year-old, playing at the World Championship for just the second time in his career, 12 years after a debut appearance, found the going tough against the man chasing a sixth title in Sheffield, and a third in succession.

O'Sullivan ploughed in a total clearance of 124 in the second frame, adding 69, 81, 60 and 90 as he moved three frames away from the second round.

Looking at ease in the familiar environment, O'Sullivan was being watched by his sports psychiatrist Dr Steve Peters, the man he credits with spurring him to the last two world titles.

Peters has also been enlisted by the Liverpool and England football teams, so successful have his associations proven with Britain's Olympic cyclists and O'Sullivan.