Ronnie O’Sullivan digs deep to reach next round of the World Snooker Championship

The 47-year-old revealed he will head straight home to bed prior to the start of his scheduled last-16 match on Friday after withstanding a strong fightback from his gutsy opponent despite feeling distinctly under the weather.

"I felt shaky, heavy and desperate," revealed O'Sullivan, who dredged up just five half-centuries in a distinctly second-gear display. "When you're feeling good you're just enjoying every ball, but I felt like I was sliding about.

"No one's ever bang on it all the time, but you have to fight through those situations. Tiger Woods had to win tours on one leg. It just saps all the energy out of you but you fight - it's a World Championship isn't it?

"I'm relieved it's over. My legs and limbs have gone. I was so desperate to get over the line in every frame. I am so tired and I can't wait to get back to my bed."

Having previously stressed the need to conserve energy during the early stages if he is to move clear of Stephen Hendry and become the first eight-time champion of the modern era, O'Sullivan was forced to fight deep into the evening session to sink his dogged opponent.

Initially it looked like Pang would provide the missteps after inexplicably managing to enter the arena via the wrong staircase, then losing the first five frames as O'Sullivan looked set to serve up the perfunctory victory he craved.

But instead it was O'Sullivan who lacked direction as Pang recovered from losing the first five frames to elbow his way back into the contest, breaking his duck with a break of 133 before winning the final two frames of the morning session to reduce his deficit to 6-3.

A break of 82 in the opening frame of the second session appeared to suggest O'Sullivan had got back on track, but he was clearly flagging and a superb 35 clearance by Pang - including an outrageous doubled red - ensured he would extend the champion beyond the final mid-session interval.

The buoyant Chinese player went further, delivering consecutive breaks of 78, 70 and 73 to haul himself back to 9-7 and extend O'Sullivan's agony.

The defending champion finally wrapped up victory with a hard-earned break of 81 in the 17th frame, and by then the fact he missed a fine opportunity to complete an historic 200th Crucible century was clearly the least of his concerns.

"I believe in the snooker gods," added O'Sullivan. "I believe they're going to do what they're going to do, and if I was going to lose tonight the gods would have determined that.

"If I'm good enough, great, and if I'm not I have to move on and take my medicine. I never get down or frustrated, because I am comfortable with my ability to play the game."

Former world champions Neil Robertson and Stuart Bingham fashioned 6-3 overnight leads against Wu Yize and David Gilbert respectively.

The Australian, who has flattered to deceive at the Crucible since his solitary title win in 2010, started in red-hot form as breaks of 138 and 96 swept him into a 3-0 lead.

Wu responded with a break of 82 and after Robertson took the next, the 19-year-old rose to the occasion with consecutive breaks of 107 to narrow the deficit to a single frame. Breaks of 64 and 80 restored Robertson's three-frame lead to conclude a high-quality session.

Bingham turned a 3-1 deficit into a 6-3 advantage against an out-of-sorts Gilbert, while Belgium's Luca Brecel racked up five half-centuries to lead

Belgium's Luca Brecel also holds a 6-3 overnight lead against Ricky Walden after racking up five half-centuries against the 2013 semi-finalist.

Qualifier Jak Jones marked his Crucible debut in style by carving a 5-4 overnight lead against former finalist Ali Carter, despite the 11th seed summoning a break of 143 in the fifth frame of the match.