In a scrappy yet enthralling encounter that swung both ways, pre-tournament favourite O’Sullivan appeared at ease after pocketing a break of 47 to take a 2-1 lead in their quarter-final clash.

However Hawkins struck back, winning the next two frames as a stunned world number one staged a remarkable fightback of his own, rattling off the next four frames in a row without reply to book his place in the last four.

O'Sullivan survived a late scare from Ding Junhui in the opening round and will be in no doubt of the need to improve when he faces Shaun Murphy - who later beat Jack Lisowski 6-3 - for a place in Sunday's final.

The 48-year-old, seemingly embarrassed to progress after missing several early chances, later apologised for his performance.

"I feel sorry for Barry. He was playing good until he started playing me," O'Sullivan told Eurosport. "I just dragged him down to probably the most awful standard of snooker.

"I’m really sorry about that today," he added. "I’m just lucky to get through, that’s all I can say."

The two other quarter-finals take place on Friday, with reigning champion Judd Trump against Ali Carter before Mark Allen faces three-time winner Mark Selby in the evening session.